diff -Nru defusedxml-0.7.1/PKG-INFO defusedxml-0.7.1/PKG-INFO --- defusedxml-0.7.1/PKG-INFO 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/PKG-INFO 2021-03-08 10:59:07.593425000 +0000 @@ -0,0 +1,976 @@ +Metadata-Version: 1.2 +Name: defusedxml +Version: 0.7.1 +Summary: XML bomb protection for Python stdlib modules +Home-page: https://github.com/tiran/defusedxml +Author: Christian Heimes +Author-email: christian@python.org +Maintainer: Christian Heimes +Maintainer-email: christian@python.org +License: PSFL +Download-URL: https://pypi.python.org/pypi/defusedxml +Description: =================================================== + defusedxml -- defusing XML bombs and other exploits + =================================================== + + .. image:: https://img.shields.io/pypi/v/defusedxml.svg + :target: https://pypi.org/project/defusedxml/ + :alt: Latest Version + + .. image:: https://img.shields.io/pypi/pyversions/defusedxml.svg + :target: https://pypi.org/project/defusedxml/ + :alt: Supported Python versions + + .. image:: https://travis-ci.org/tiran/defusedxml.svg?branch=master + :target: https://travis-ci.org/tiran/defusedxml + :alt: Travis CI + + .. image:: https://codecov.io/github/tiran/defusedxml/coverage.svg?branch=master + :target: https://codecov.io/github/tiran/defusedxml?branch=master + :alt: codecov + + .. image:: https://img.shields.io/pypi/dm/defusedxml.svg + :target: https://pypistats.org/packages/defusedxml + :alt: PyPI downloads + + .. image:: https://img.shields.io/badge/code%20style-black-000000.svg + :target: https://github.com/psf/black + :alt: Code style: black + + .. + + "It's just XML, what could probably go wrong?" + + Christian Heimes + + Synopsis + ======== + + The results of an attack on a vulnerable XML library can be fairly dramatic. + With just a few hundred **Bytes** of XML data an attacker can occupy several + **Gigabytes** of memory within **seconds**. An attacker can also keep + CPUs busy for a long time with a small to medium size request. Under some + circumstances it is even possible to access local files on your + server, to circumvent a firewall, or to abuse services to rebound attacks to + third parties. + + The attacks use and abuse less common features of XML and its parsers. The + majority of developers are unacquainted with features such as processing + instructions and entity expansions that XML inherited from SGML. At best + they know about ```` from experience with HTML but they are not + aware that a document type definition (DTD) can generate an HTTP request + or load a file from the file system. + + None of the issues is new. They have been known for a long time. Billion + laughs was first reported in 2003. Nevertheless some XML libraries and + applications are still vulnerable and even heavy users of XML are + surprised by these features. It's hard to say whom to blame for the + situation. It's too short sighted to shift all blame on XML parsers and + XML libraries for using insecure default settings. After all they + properly implement XML specifications. Application developers must not rely + that a library is always configured for security and potential harmful data + by default. + + + .. contents:: Table of Contents + :depth: 2 + + + Attack vectors + ============== + + billion laughs / exponential entity expansion + --------------------------------------------- + + The `Billion Laughs`_ attack -- also known as exponential entity expansion -- + uses multiple levels of nested entities. The original example uses 9 levels + of 10 expansions in each level to expand the string ``lol`` to a string of + 3 * 10 :sup:`9` bytes, hence the name "billion laughs". The resulting string + occupies 3 GB (2.79 GiB) of memory; intermediate strings require additional + memory. Because most parsers don't cache the intermediate step for every + expansion it is repeated over and over again. It increases the CPU load even + more. + + An XML document of just a few hundred bytes can disrupt all services on a + machine within seconds. + + Example XML:: + + + + + + ]> + &d; + + + quadratic blowup entity expansion + --------------------------------- + + A quadratic blowup attack is similar to a `Billion Laughs`_ attack; it abuses + entity expansion, too. Instead of nested entities it repeats one large entity + with a couple of thousand chars over and over again. The attack isn't as + efficient as the exponential case but it avoids triggering countermeasures of + parsers against heavily nested entities. Some parsers limit the depth and + breadth of a single entity but not the total amount of expanded text + throughout an entire XML document. + + A medium-sized XML document with a couple of hundred kilobytes can require a + couple of hundred MB to several GB of memory. When the attack is combined + with some level of nested expansion an attacker is able to achieve a higher + ratio of success. + + :: + + + ]> + &a;&a;&a;... repeat + + + external entity expansion (remote) + ---------------------------------- + + Entity declarations can contain more than just text for replacement. They can + also point to external resources by public identifiers or system identifiers. + System identifiers are standard URIs. When the URI is a URL (e.g. a + ``http://`` locator) some parsers download the resource from the remote + location and embed them into the XML document verbatim. + + Simple example of a parsed external entity:: + + + ]> + + + The case of parsed external entities works only for valid XML content. The + XML standard also supports unparsed external entities with a + ``NData declaration``. + + External entity expansion opens the door to plenty of exploits. An attacker + can abuse a vulnerable XML library and application to rebound and forward + network requests with the IP address of the server. It highly depends + on the parser and the application what kind of exploit is possible. For + example: + + * An attacker can circumvent firewalls and gain access to restricted + resources as all the requests are made from an internal and trustworthy + IP address, not from the outside. + * An attacker can abuse a service to attack, spy on or DoS your servers but + also third party services. The attack is disguised with the IP address of + the server and the attacker is able to utilize the high bandwidth of a big + machine. + * An attacker can exhaust additional resources on the machine, e.g. with + requests to a service that doesn't respond or responds with very large + files. + * An attacker may gain knowledge, when, how often and from which IP address + an XML document is accessed. + * An attacker could send mail from inside your network if the URL handler + supports ``smtp://`` URIs. + + + external entity expansion (local file) + -------------------------------------- + + External entities with references to local files are a sub-case of external + entity expansion. It's listed as an extra attack because it deserves extra + attention. Some XML libraries such as lxml disable network access by default + but still allow entity expansion with local file access by default. Local + files are either referenced with a ``file://`` URL or by a file path (either + relative or absolute). + + An attacker may be able to access and download all files that can be read by + the application process. This may include critical configuration files, too. + + :: + + + ]> + + + + DTD retrieval + ------------- + + This case is similar to external entity expansion, too. Some XML libraries + like Python's xml.dom.pulldom retrieve document type definitions from remote + or local locations. Several attack scenarios from the external entity case + apply to this issue as well. + + :: + + + + + + text + + + + Python XML Libraries + ==================== + + .. csv-table:: vulnerabilities and features + :header: "kind", "sax", "etree", "minidom", "pulldom", "xmlrpc", "lxml", "genshi" + :widths: 24, 7, 8, 8, 7, 8, 8, 8 + :stub-columns: 0 + + "billion laughs", "**True**", "**True**", "**True**", "**True**", "**True**", "False (1)", "False (5)" + "quadratic blowup", "**True**", "**True**", "**True**", "**True**", "**True**", "**True**", "False (5)" + "external entity expansion (remote)", "**True**", "False (3)", "False (4)", "**True**", "false", "False (1)", "False (5)" + "external entity expansion (local file)", "**True**", "False (3)", "False (4)", "**True**", "false", "**True**", "False (5)" + "DTD retrieval", "**True**", "False", "False", "**True**", "false", "False (1)", "False" + "gzip bomb", "False", "False", "False", "False", "**True**", "**partly** (2)", "False" + "xpath support (7)", "False", "False", "False", "False", "False", "**True**", "False" + "xsl(t) support (7)", "False", "False", "False", "False", "False", "**True**", "False" + "xinclude support (7)", "False", "**True** (6)", "False", "False", "False", "**True** (6)", "**True**" + "C library", "expat", "expat", "expat", "expat", "expat", "libxml2", "expat" + + 1. Lxml is protected against billion laughs attacks and doesn't do network + lookups by default. + 2. libxml2 and lxml are not directly vulnerable to gzip decompression bombs + but they don't protect you against them either. + 3. xml.etree doesn't expand entities and raises a ParserError when an entity + occurs. + 4. minidom doesn't expand entities and simply returns the unexpanded entity + verbatim. + 5. genshi.input of genshi 0.6 doesn't support entity expansion and raises a + ParserError when an entity occurs. + 6. Library has (limited) XInclude support but requires an additional step to + process inclusion. + 7. These are features but they may introduce exploitable holes, see + `Other things to consider`_ + + + Settings in standard library + ---------------------------- + + + xml.sax.handler Features + ........................ + + feature_external_ges (http://xml.org/sax/features/external-general-entities) + disables external entity expansion + + feature_external_pes (http://xml.org/sax/features/external-parameter-entities) + the option is ignored and doesn't modify any functionality + + DOM xml.dom.xmlbuilder.Options + .............................. + + external_parameter_entities + ignored + + external_general_entities + ignored + + external_dtd_subset + ignored + + entities + unsure + + + defusedxml + ========== + + The `defusedxml package`_ (`defusedxml on PyPI`_) + contains several Python-only workarounds and fixes + for denial of service and other vulnerabilities in Python's XML libraries. + In order to benefit from the protection you just have to import and use the + listed functions / classes from the right defusedxml module instead of the + original module. Merely `defusedxml.xmlrpc`_ is implemented as monkey patch. + + Instead of:: + + >>> from xml.etree.ElementTree import parse + >>> et = parse(xmlfile) + + alter code to:: + + >>> from defusedxml.ElementTree import parse + >>> et = parse(xmlfile) + + Additionally the package has an **untested** function to monkey patch + all stdlib modules with ``defusedxml.defuse_stdlib()``. + + All functions and parser classes accept three additional keyword arguments. + They return either the same objects as the original functions or compatible + subclasses. + + forbid_dtd (default: False) + disallow XML with a ```` processing instruction and raise a + *DTDForbidden* exception when a DTD processing instruction is found. + + forbid_entities (default: True) + disallow XML with ```` declarations inside the DTD and raise an + *EntitiesForbidden* exception when an entity is declared. + + forbid_external (default: True) + disallow any access to remote or local resources in external entities + or DTD and raising an *ExternalReferenceForbidden* exception when a DTD + or entity references an external resource. + + + defusedxml (package) + -------------------- + + DefusedXmlException, DTDForbidden, EntitiesForbidden, + ExternalReferenceForbidden, NotSupportedError + + defuse_stdlib() (*experimental*) + + + defusedxml.cElementTree + ----------------------- + + **NOTE** ``defusedxml.cElementTree`` is deprecated and will be removed in a + future release. Import from ``defusedxml.ElementTree`` instead. + + parse(), iterparse(), fromstring(), XMLParser + + + defusedxml.ElementTree + ----------------------- + + parse(), iterparse(), fromstring(), XMLParser + + + defusedxml.expatreader + ---------------------- + + create_parser(), DefusedExpatParser + + + defusedxml.sax + -------------- + + parse(), parseString(), make_parser() + + + defusedxml.expatbuilder + ----------------------- + + parse(), parseString(), DefusedExpatBuilder, DefusedExpatBuilderNS + + + defusedxml.minidom + ------------------ + + parse(), parseString() + + + defusedxml.pulldom + ------------------ + + parse(), parseString() + + + defusedxml.xmlrpc + ----------------- + + The fix is implemented as monkey patch for the stdlib's xmlrpc package (3.x) + or xmlrpclib module (2.x). The function `monkey_patch()` enables the fixes, + `unmonkey_patch()` removes the patch and puts the code in its former state. + + The monkey patch protects against XML related attacks as well as + decompression bombs and excessively large requests or responses. The default + setting is 30 MB for requests, responses and gzip decompression. You can + modify the default by changing the module variable `MAX_DATA`. A value of + `-1` disables the limit. + + + defusedxml.lxml + --------------- + + **DEPRECATED** The module is deprecated and will be removed in a future + release. + + The module acts as an *example* how you could protect code that uses + lxml.etree. It implements a custom Element class that filters out + Entity instances, a custom parser factory and a thread local storage for + parser instances. It also has a check_docinfo() function which inspects + a tree for internal or external DTDs and entity declarations. In order to + check for entities lxml > 3.0 is required. + + parse(), fromstring() + RestrictedElement, GlobalParserTLS, getDefaultParser(), check_docinfo() + + + defusedexpat + ============ + + The `defusedexpat package`_ (`defusedexpat on PyPI`_) + comes with binary extensions and a + `modified expat`_ library instead of the standard `expat parser`_. It's + basically a stand-alone version of the patches for Python's standard + library C extensions. + + Modifications in expat + ---------------------- + + new definitions:: + + XML_BOMB_PROTECTION + XML_DEFAULT_MAX_ENTITY_INDIRECTIONS + XML_DEFAULT_MAX_ENTITY_EXPANSIONS + XML_DEFAULT_RESET_DTD + + new XML_FeatureEnum members:: + + XML_FEATURE_MAX_ENTITY_INDIRECTIONS + XML_FEATURE_MAX_ENTITY_EXPANSIONS + XML_FEATURE_IGNORE_DTD + + new XML_Error members:: + + XML_ERROR_ENTITY_INDIRECTIONS + XML_ERROR_ENTITY_EXPANSION + + new API functions:: + + int XML_GetFeature(XML_Parser parser, + enum XML_FeatureEnum feature, + long *value); + int XML_SetFeature(XML_Parser parser, + enum XML_FeatureEnum feature, + long value); + int XML_GetFeatureDefault(enum XML_FeatureEnum feature, + long *value); + int XML_SetFeatureDefault(enum XML_FeatureEnum feature, + long value); + + XML_FEATURE_MAX_ENTITY_INDIRECTIONS + Limit the amount of indirections that are allowed to occur during the + expansion of a nested entity. A counter starts when an entity reference + is encountered. It resets after the entity is fully expanded. The limit + protects the parser against exponential entity expansion attacks (aka + billion laughs attack). When the limit is exceeded the parser stops and + fails with `XML_ERROR_ENTITY_INDIRECTIONS`. + A value of 0 disables the protection. + + Supported range + 0 .. UINT_MAX + Default + 40 + + XML_FEATURE_MAX_ENTITY_EXPANSIONS + Limit the total length of all entity expansions throughout the entire + document. The lengths of all entities are accumulated in a parser variable. + The setting protects against quadratic blowup attacks (lots of expansions + of a large entity declaration). When the sum of all entities exceeds + the limit, the parser stops and fails with `XML_ERROR_ENTITY_EXPANSION`. + A value of 0 disables the protection. + + Supported range + 0 .. UINT_MAX + Default + 8 MiB + + XML_FEATURE_RESET_DTD + Reset all DTD information after the block has been parsed. When + the flag is set (default: false) all DTD information after the + endDoctypeDeclHandler has been called. The flag can be set inside the + endDoctypeDeclHandler. Without DTD information any entity reference in + the document body leads to `XML_ERROR_UNDEFINED_ENTITY`. + + Supported range + 0, 1 + Default + 0 + + + How to avoid XML vulnerabilities + ================================ + + Best practices + -------------- + + * Don't allow DTDs + * Don't expand entities + * Don't resolve externals + * Limit parse depth + * Limit total input size + * Limit parse time + * Favor a SAX or iterparse-like parser for potential large data + * Validate and properly quote arguments to XSL transformations and + XPath queries + * Don't use XPath expression from untrusted sources + * Don't apply XSL transformations that come untrusted sources + + (based on Brad Hill's `Attacking XML Security`_) + + + Other things to consider + ======================== + + XML, XML parsers and processing libraries have more features and possible + issue that could lead to DoS vulnerabilities or security exploits in + applications. I have compiled an incomplete list of theoretical issues that + need further research and more attention. The list is deliberately pessimistic + and a bit paranoid, too. It contains things that might go wrong under daffy + circumstances. + + + attribute blowup / hash collision attack + ---------------------------------------- + + XML parsers may use an algorithm with quadratic runtime O(n :sup:`2`) to + handle attributes and namespaces. If it uses hash tables (dictionaries) to + store attributes and namespaces the implementation may be vulnerable to + hash collision attacks, thus reducing the performance to O(n :sup:`2`) again. + In either case an attacker is able to forge a denial of service attack with + an XML document that contains thousands upon thousands of attributes in + a single node. + + I haven't researched yet if expat, pyexpat or libxml2 are vulnerable. + + + decompression bomb + ------------------ + + The issue of decompression bombs (aka `ZIP bomb`_) apply to all XML libraries + that can parse compressed XML stream like gzipped HTTP streams or LZMA-ed + files. For an attacker it can reduce the amount of transmitted data by three + magnitudes or more. Gzip is able to compress 1 GiB zeros to roughly 1 MB, + lzma is even better:: + + $ dd if=/dev/zero bs=1M count=1024 | gzip > zeros.gz + $ dd if=/dev/zero bs=1M count=1024 | lzma -z > zeros.xy + $ ls -sh zeros.* + 1020K zeros.gz + 148K zeros.xy + + None of Python's standard XML libraries decompress streams except for + ``xmlrpclib``. The module is vulnerable + to decompression bombs. + + lxml can load and process compressed data through libxml2 transparently. + libxml2 can handle even very large blobs of compressed data efficiently + without using too much memory. But it doesn't protect applications from + decompression bombs. A carefully written SAX or iterparse-like approach can + be safe. + + + Processing Instruction + ---------------------- + + `PI`_'s like:: + + + + may impose more threats for XML processing. It depends if and how a + processor handles processing instructions. The issue of URL retrieval with + network or local file access apply to processing instructions, too. + + + Other DTD features + ------------------ + + `DTD`_ has more features like ````. I haven't researched how + these features may be a security threat. + + + XPath + ----- + + XPath statements may introduce DoS vulnerabilities. Code should never execute + queries from untrusted sources. An attacker may also be able to create an XML + document that makes certain XPath queries costly or resource hungry. + + + XPath injection attacks + ----------------------- + + XPath injeciton attacks pretty much work like SQL injection attacks. + Arguments to XPath queries must be quoted and validated properly, especially + when they are taken from the user. The page `Avoid the dangers of XPath injection`_ + list some ramifications of XPath injections. + + Python's standard library doesn't have XPath support. Lxml supports + parameterized XPath queries which does proper quoting. You just have to use + its xpath() method correctly:: + + # DON'T + >>> tree.xpath("/tag[@id='%s']" % value) + + # instead do + >>> tree.xpath("/tag[@id=$tagid]", tagid=name) + + + XInclude + -------- + + `XML Inclusion`_ is another way to load and include external files:: + + + + + + This feature should be disabled when XML files from an untrusted source are + processed. Some Python XML libraries and libxml2 support XInclude but don't + have an option to sandbox inclusion and limit it to allowed directories. + + + XMLSchema location + ------------------ + + A validating XML parser may download schema files from the information in a + ``xsi:schemaLocation`` attribute. + + :: + + + + + + XSL Transformation + ------------------ + + You should keep in mind that XSLT is a Turing complete language. Never + process XSLT code from unknown or untrusted source! XSLT processors may + allow you to interact with external resources in ways you can't even imagine. + Some processors even support extensions that allow read/write access to file + system, access to JRE objects or scripting with Jython. + + Example from `Attacking XML Security`_ for Xalan-J:: + + + + + + + + + + + + Related CVEs + ============ + + CVE-2013-1664 + Unrestricted entity expansion induces DoS vulnerabilities in Python XML + libraries (XML bomb) + + CVE-2013-1665 + External entity expansion in Python XML libraries inflicts potential + security flaws and DoS vulnerabilities + + + Other languages / frameworks + ============================= + + Several other programming languages and frameworks are vulnerable as well. A + couple of them are affected by the fact that libxml2 up to 2.9.0 has no + protection against quadratic blowup attacks. Most of them have potential + dangerous default settings for entity expansion and external entities, too. + + Perl + ---- + + Perl's XML::Simple is vulnerable to quadratic entity expansion and external + entity expansion (both local and remote). + + + Ruby + ---- + + Ruby's REXML document parser is vulnerable to entity expansion attacks + (both quadratic and exponential) but it doesn't do external entity + expansion by default. In order to counteract entity expansion you have to + disable the feature:: + + REXML::Document.entity_expansion_limit = 0 + + libxml-ruby and hpricot don't expand entities in their default configuration. + + + PHP + --- + + PHP's SimpleXML API is vulnerable to quadratic entity expansion and loads + entities from local and remote resources. The option ``LIBXML_NONET`` disables + network access but still allows local file access. ``LIBXML_NOENT`` seems to + have no effect on entity expansion in PHP 5.4.6. + + + C# / .NET / Mono + ---------------- + + Information in `XML DoS and Defenses (MSDN)`_ suggest that .NET is + vulnerable with its default settings. The article contains code snippets + how to create a secure XML reader:: + + XmlReaderSettings settings = new XmlReaderSettings(); + settings.ProhibitDtd = false; + settings.MaxCharactersFromEntities = 1024; + settings.XmlResolver = null; + XmlReader reader = XmlReader.Create(stream, settings); + + + Java + ---- + + Untested. The documentation of Xerces and its `Xerces SecurityMananger`_ + sounds like Xerces is also vulnerable to billion laugh attacks with its + default settings. It also does entity resolving when an + ``org.xml.sax.EntityResolver`` is configured. I'm not yet sure about the + default setting here. + + Java specialists suggest to have a custom builder factory:: + + DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance(); + builderFactory.setXIncludeAware(False); + builderFactory.setExpandEntityReferences(False); + builderFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, True); + # either + builderFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", True); + # or if you need DTDs + builderFactory.setFeature("http://xml.org/sax/features/external-general-entities", False); + builderFactory.setFeature("http://xml.org/sax/features/external-parameter-entities", False); + builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", False); + builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-dtd-grammar", False); + + + TODO + ==== + + * DOM: Use xml.dom.xmlbuilder options for entity handling + * SAX: take feature_external_ges and feature_external_pes (?) into account + * test experimental monkey patching of stdlib modules + * improve documentation + + + License + ======= + + Copyright (c) 2013-2017 by Christian Heimes + + Licensed to PSF under a Contributor Agreement. + + See https://www.python.org/psf/license for licensing details. + + + Acknowledgements + ================ + + Brett Cannon (Python Core developer) + review and code cleanup + + Antoine Pitrou (Python Core developer) + code review + + Aaron Patterson, Ben Murphy and Michael Koziarski (Ruby community) + Many thanks to Aaron, Ben and Michael from the Ruby community for their + report and assistance. + + Thierry Carrez (OpenStack) + Many thanks to Thierry for his report to the Python Security Response + Team on behalf of the OpenStack security team. + + Carl Meyer (Django) + Many thanks to Carl for his report to PSRT on behalf of the Django security + team. + + Daniel Veillard (libxml2) + Many thanks to Daniel for his insight and assistance with libxml2. + + semantics GmbH (https://www.semantics.de/) + Many thanks to my employer semantics for letting me work on the issue + during working hours as part of semantics's open source initiative. + + + References + ========== + + * `XML DoS and Defenses (MSDN)`_ + * `Billion Laughs`_ on Wikipedia + * `ZIP bomb`_ on Wikipedia + * `Configure SAX parsers for secure processing`_ + * `Testing for XML Injection`_ + + .. _defusedxml package: https://github.com/tiran/defusedxml + .. _defusedxml on PyPI: https://pypi.python.org/pypi/defusedxml + .. _defusedexpat package: https://github.com/tiran/defusedexpat + .. _defusedexpat on PyPI: https://pypi.python.org/pypi/defusedexpat + .. _modified expat: https://github.com/tiran/expat + .. _expat parser: http://expat.sourceforge.net/ + .. _Attacking XML Security: https://www.isecpartners.com/media/12976/iSEC-HILL-Attacking-XML-Security-bh07.pdf + .. _Billion Laughs: https://en.wikipedia.org/wiki/Billion_laughs + .. _XML DoS and Defenses (MSDN): https://msdn.microsoft.com/en-us/magazine/ee335713.aspx + .. _ZIP bomb: https://en.wikipedia.org/wiki/Zip_bomb + .. _DTD: https://en.wikipedia.org/wiki/Document_Type_Definition + .. _PI: https://en.wikipedia.org/wiki/Processing_Instruction + .. _Avoid the dangers of XPath injection: http://www.ibm.com/developerworks/xml/library/x-xpathinjection/index.html + .. _Configure SAX parsers for secure processing: http://www.ibm.com/developerworks/xml/library/x-tipcfsx/index.html + .. _Testing for XML Injection: https://www.owasp.org/index.php/Testing_for_XML_Injection_(OWASP-DV-008) + .. _Xerces SecurityMananger: https://xerces.apache.org/xerces2-j/javadocs/xerces2/org/apache/xerces/util/SecurityManager.html + .. _XML Inclusion: https://www.w3.org/TR/xinclude/#include_element + + Changelog + ========= + + defusedxml 0.7.1 + --------------------- + + *Release date: 08-Mar-2021* + + - Fix regression ``defusedxml.ElementTree.ParseError`` (#63) + The ``ParseError`` exception is now the same class object as + ``xml.etree.ElementTree.ParseError`` again. + + + defusedxml 0.7.0 + ---------------- + + *Release date: 4-Mar-2021* + + - No changes + + + defusedxml 0.7.0rc2 + ------------------- + + *Release date: 12-Jan-2021* + + - Re-add and deprecate ``defusedxml.cElementTree`` + - Use GitHub Actions instead of TravisCI + - Restore ``ElementTree`` attribute of ``xml.etree`` module after patching + + defusedxml 0.7.0rc1 + ------------------- + + *Release date: 04-May-2020* + + - Add support for Python 3.9 + - ``defusedxml.cElementTree`` is not available with Python 3.9. + - Python 2 is deprecate. Support for Python 2 will be removed in 0.8.0. + + + defusedxml 0.6.0 + ---------------- + + *Release date: 17-Apr-2019* + + - Increase test coverage. + - Add badges to README. + + + defusedxml 0.6.0rc1 + ------------------- + + *Release date: 14-Apr-2019* + + - Test on Python 3.7 stable and 3.8-dev + - Drop support for Python 3.4 + - No longer pass *html* argument to XMLParse. It has been deprecated and + ignored for a long time. The DefusedXMLParser still takes a html argument. + A deprecation warning is issued when the argument is False and a TypeError + when it's True. + - defusedxml now fails early when pyexpat stdlib module is not available or + broken. + - defusedxml.ElementTree.__all__ now lists ParseError as public attribute. + - The defusedxml.ElementTree and defusedxml.cElementTree modules had a typo + and used XMLParse instead of XMLParser as an alias for DefusedXMLParser. + Both the old and fixed name are now available. + + + defusedxml 0.5.0 + ---------------- + + *Release date: 07-Feb-2017* + + - No changes + + + defusedxml 0.5.0.rc1 + -------------------- + + *Release date: 28-Jan-2017* + + - Add compatibility with Python 3.6 + - Drop support for Python 2.6, 3.1, 3.2, 3.3 + - Fix lxml tests (XMLSyntaxError: Detected an entity reference loop) + + + defusedxml 0.4.1 + ---------------- + + *Release date: 28-Mar-2013* + + - Add more demo exploits, e.g. python_external.py and Xalan XSLT demos. + - Improved documentation. + + + defusedxml 0.4 + -------------- + + *Release date: 25-Feb-2013* + + - As per http://seclists.org/oss-sec/2013/q1/340 please REJECT + CVE-2013-0278, CVE-2013-0279 and CVE-2013-0280 and use CVE-2013-1664, + CVE-2013-1665 for OpenStack/etc. + - Add missing parser_list argument to sax.make_parser(). The argument is + ignored, though. (thanks to Florian Apolloner) + - Add demo exploit for external entity attack on Python's SAX parser, XML-RPC + and WebDAV. + + + defusedxml 0.3 + -------------- + + *Release date: 19-Feb-2013* + + - Improve documentation + + + defusedxml 0.2 + -------------- + + *Release date: 15-Feb-2013* + + - Rename ExternalEntitiesForbidden to ExternalReferenceForbidden + - Rename defusedxml.lxml.check_dtd() to check_docinfo() + - Unify argument names in callbacks + - Add arguments and formatted representation to exceptions + - Add forbid_external argument to all functions and classes + - More tests + - LOTS of documentation + - Add example code for other languages (Ruby, Perl, PHP) and parsers (Genshi) + - Add protection against XML and gzip attacks to xmlrpclib + + defusedxml 0.1 + -------------- + + *Release date: 08-Feb-2013* + + - Initial and internal release for PSRT review + +Keywords: xml bomb DoS +Platform: all +Classifier: Development Status :: 5 - Production/Stable +Classifier: Intended Audience :: Developers +Classifier: License :: OSI Approved :: Python Software Foundation License +Classifier: Natural Language :: English +Classifier: Programming Language :: Python +Classifier: Programming Language :: Python :: 2 +Classifier: Programming Language :: Python :: 2.7 +Classifier: Programming Language :: Python :: 3 +Classifier: Programming Language :: Python :: 3.5 +Classifier: Programming Language :: Python :: 3.6 +Classifier: Programming Language :: Python :: 3.7 +Classifier: Programming Language :: Python :: 3.8 +Classifier: Programming Language :: Python :: 3.9 +Classifier: Topic :: Text Processing :: Markup :: XML +Requires-Python: >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.* diff -Nru defusedxml-0.7.1/README.html defusedxml-0.7.1/README.html --- defusedxml-0.7.1/README.html 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/README.html 2021-03-08 10:57:28.000000000 +0000 @@ -0,0 +1,1444 @@ + + + + + + +defusedxml -- defusing XML bombs and other exploits + + + +
+

defusedxml -- defusing XML bombs and other exploits

+ +Latest Version +Supported Python versions +Travis CI +codecov +PyPI downloads +Code style: black + +
+"It's just XML, what could probably go wrong?"
+

Christian Heimes <christian@python.org>

+
+

Synopsis

+

The results of an attack on a vulnerable XML library can be fairly dramatic. +With just a few hundred Bytes of XML data an attacker can occupy several +Gigabytes of memory within seconds. An attacker can also keep +CPUs busy for a long time with a small to medium size request. Under some +circumstances it is even possible to access local files on your +server, to circumvent a firewall, or to abuse services to rebound attacks to +third parties.

+

The attacks use and abuse less common features of XML and its parsers. The +majority of developers are unacquainted with features such as processing +instructions and entity expansions that XML inherited from SGML. At best +they know about <!DOCTYPE> from experience with HTML but they are not +aware that a document type definition (DTD) can generate an HTTP request +or load a file from the file system.

+

None of the issues is new. They have been known for a long time. Billion +laughs was first reported in 2003. Nevertheless some XML libraries and +applications are still vulnerable and even heavy users of XML are +surprised by these features. It's hard to say whom to blame for the +situation. It's too short sighted to shift all blame on XML parsers and +XML libraries for using insecure default settings. After all they +properly implement XML specifications. Application developers must not rely +that a library is always configured for security and potential harmful data +by default.

+ +
+
+

Attack vectors

+
+

billion laughs / exponential entity expansion

+

The Billion Laughs attack -- also known as exponential entity expansion -- +uses multiple levels of nested entities. The original example uses 9 levels +of 10 expansions in each level to expand the string lol to a string of +3 * 10 9 bytes, hence the name "billion laughs". The resulting string +occupies 3 GB (2.79 GiB) of memory; intermediate strings require additional +memory. Because most parsers don't cache the intermediate step for every +expansion it is repeated over and over again. It increases the CPU load even +more.

+

An XML document of just a few hundred bytes can disrupt all services on a +machine within seconds.

+

Example XML:

+
+<!DOCTYPE xmlbomb [
+<!ENTITY a "1234567890" >
+<!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;">
+<!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;">
+<!ENTITY d "&c;&c;&c;&c;&c;&c;&c;&c;">
+]>
+<bomb>&d;</bomb>
+
+
+
+

quadratic blowup entity expansion

+

A quadratic blowup attack is similar to a Billion Laughs attack; it abuses +entity expansion, too. Instead of nested entities it repeats one large entity +with a couple of thousand chars over and over again. The attack isn't as +efficient as the exponential case but it avoids triggering countermeasures of +parsers against heavily nested entities. Some parsers limit the depth and +breadth of a single entity but not the total amount of expanded text +throughout an entire XML document.

+

A medium-sized XML document with a couple of hundred kilobytes can require a +couple of hundred MB to several GB of memory. When the attack is combined +with some level of nested expansion an attacker is able to achieve a higher +ratio of success.

+
+<!DOCTYPE bomb [
+<!ENTITY a "xxxxxxx... a couple of ten thousand chars">
+]>
+<bomb>&a;&a;&a;... repeat</bomb>
+
+
+
+

external entity expansion (remote)

+

Entity declarations can contain more than just text for replacement. They can +also point to external resources by public identifiers or system identifiers. +System identifiers are standard URIs. When the URI is a URL (e.g. a +http:// locator) some parsers download the resource from the remote +location and embed them into the XML document verbatim.

+

Simple example of a parsed external entity:

+
+<!DOCTYPE external [
+<!ENTITY ee SYSTEM "http://www.python.org/some.xml">
+]>
+<root>&ee;</root>
+
+

The case of parsed external entities works only for valid XML content. The +XML standard also supports unparsed external entities with a +NData declaration.

+

External entity expansion opens the door to plenty of exploits. An attacker +can abuse a vulnerable XML library and application to rebound and forward +network requests with the IP address of the server. It highly depends +on the parser and the application what kind of exploit is possible. For +example:

+
    +
  • An attacker can circumvent firewalls and gain access to restricted +resources as all the requests are made from an internal and trustworthy +IP address, not from the outside.
  • +
  • An attacker can abuse a service to attack, spy on or DoS your servers but +also third party services. The attack is disguised with the IP address of +the server and the attacker is able to utilize the high bandwidth of a big +machine.
  • +
  • An attacker can exhaust additional resources on the machine, e.g. with +requests to a service that doesn't respond or responds with very large +files.
  • +
  • An attacker may gain knowledge, when, how often and from which IP address +an XML document is accessed.
  • +
  • An attacker could send mail from inside your network if the URL handler +supports smtp:// URIs.
  • +
+
+
+

external entity expansion (local file)

+

External entities with references to local files are a sub-case of external +entity expansion. It's listed as an extra attack because it deserves extra +attention. Some XML libraries such as lxml disable network access by default +but still allow entity expansion with local file access by default. Local +files are either referenced with a file:// URL or by a file path (either +relative or absolute).

+

An attacker may be able to access and download all files that can be read by +the application process. This may include critical configuration files, too.

+
+<!DOCTYPE external [
+<!ENTITY ee SYSTEM "file:///PATH/TO/simple.xml">
+]>
+<root>&ee;</root>
+
+
+
+

DTD retrieval

+

This case is similar to external entity expansion, too. Some XML libraries +like Python's xml.dom.pulldom retrieve document type definitions from remote +or local locations. Several attack scenarios from the external entity case +apply to this issue as well.

+
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html>
+    <head/>
+    <body>text</body>
+</html>
+
+
+
+
+

Python XML Libraries

+ + ++++++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
vulnerabilities and features
kindsaxetreeminidompulldomxmlrpclxmlgenshi
billion laughsTrueTrueTrueTrueTrueFalse (1)False (5)
quadratic blowupTrueTrueTrueTrueTrueTrueFalse (5)
external entity expansion (remote)TrueFalse (3)False (4)TruefalseFalse (1)False (5)
external entity expansion (local file)TrueFalse (3)False (4)TruefalseTrueFalse (5)
DTD retrievalTrueFalseFalseTruefalseFalse (1)False
gzip bombFalseFalseFalseFalseTruepartly (2)False
xpath support (7)FalseFalseFalseFalseFalseTrueFalse
xsl(t) support (7)FalseFalseFalseFalseFalseTrueFalse
xinclude support (7)FalseTrue (6)FalseFalseFalseTrue (6)True
C libraryexpatexpatexpatexpatexpatlibxml2expat
+
    +
  1. Lxml is protected against billion laughs attacks and doesn't do network +lookups by default.
  2. +
  3. libxml2 and lxml are not directly vulnerable to gzip decompression bombs +but they don't protect you against them either.
  4. +
  5. xml.etree doesn't expand entities and raises a ParserError when an entity +occurs.
  6. +
  7. minidom doesn't expand entities and simply returns the unexpanded entity +verbatim.
  8. +
  9. genshi.input of genshi 0.6 doesn't support entity expansion and raises a +ParserError when an entity occurs.
  10. +
  11. Library has (limited) XInclude support but requires an additional step to +process inclusion.
  12. +
  13. These are features but they may introduce exploitable holes, see +Other things to consider
  14. +
+
+

Settings in standard library

+
+

xml.sax.handler Features

+
+
feature_external_ges (http://xml.org/sax/features/external-general-entities)
+
disables external entity expansion
+
feature_external_pes (http://xml.org/sax/features/external-parameter-entities)
+
the option is ignored and doesn't modify any functionality
+
+
+
+

DOM xml.dom.xmlbuilder.Options

+
+
external_parameter_entities
+
ignored
+
external_general_entities
+
ignored
+
external_dtd_subset
+
ignored
+
entities
+
unsure
+
+
+
+
+
+

defusedxml

+

The defusedxml package (defusedxml on PyPI) +contains several Python-only workarounds and fixes +for denial of service and other vulnerabilities in Python's XML libraries. +In order to benefit from the protection you just have to import and use the +listed functions / classes from the right defusedxml module instead of the +original module. Merely defusedxml.xmlrpc is implemented as monkey patch.

+

Instead of:

+
+>>> from xml.etree.ElementTree import parse
+>>> et = parse(xmlfile)
+
+

alter code to:

+
+>>> from defusedxml.ElementTree import parse
+>>> et = parse(xmlfile)
+
+

Additionally the package has an untested function to monkey patch +all stdlib modules with defusedxml.defuse_stdlib().

+

All functions and parser classes accept three additional keyword arguments. +They return either the same objects as the original functions or compatible +subclasses.

+
+
forbid_dtd (default: False)
+
disallow XML with a <!DOCTYPE> processing instruction and raise a +DTDForbidden exception when a DTD processing instruction is found.
+
forbid_entities (default: True)
+
disallow XML with <!ENTITY> declarations inside the DTD and raise an +EntitiesForbidden exception when an entity is declared.
+
forbid_external (default: True)
+
disallow any access to remote or local resources in external entities +or DTD and raising an ExternalReferenceForbidden exception when a DTD +or entity references an external resource.
+
+
+

defusedxml (package)

+

DefusedXmlException, DTDForbidden, EntitiesForbidden, +ExternalReferenceForbidden, NotSupportedError

+

defuse_stdlib() (experimental)

+
+
+

defusedxml.cElementTree

+

NOTE defusedxml.cElementTree is deprecated and will be removed in a +future release. Import from defusedxml.ElementTree instead.

+

parse(), iterparse(), fromstring(), XMLParser

+
+
+

defusedxml.ElementTree

+

parse(), iterparse(), fromstring(), XMLParser

+
+
+

defusedxml.expatreader

+

create_parser(), DefusedExpatParser

+
+
+

defusedxml.sax

+

parse(), parseString(), make_parser()

+
+
+

defusedxml.expatbuilder

+

parse(), parseString(), DefusedExpatBuilder, DefusedExpatBuilderNS

+
+
+

defusedxml.minidom

+

parse(), parseString()

+
+
+

defusedxml.pulldom

+

parse(), parseString()

+
+
+

defusedxml.xmlrpc

+

The fix is implemented as monkey patch for the stdlib's xmlrpc package (3.x) +or xmlrpclib module (2.x). The function monkey_patch() enables the fixes, +unmonkey_patch() removes the patch and puts the code in its former state.

+

The monkey patch protects against XML related attacks as well as +decompression bombs and excessively large requests or responses. The default +setting is 30 MB for requests, responses and gzip decompression. You can +modify the default by changing the module variable MAX_DATA. A value of +-1 disables the limit.

+
+
+

defusedxml.lxml

+

DEPRECATED The module is deprecated and will be removed in a future +release.

+

The module acts as an example how you could protect code that uses +lxml.etree. It implements a custom Element class that filters out +Entity instances, a custom parser factory and a thread local storage for +parser instances. It also has a check_docinfo() function which inspects +a tree for internal or external DTDs and entity declarations. In order to +check for entities lxml > 3.0 is required.

+

parse(), fromstring() +RestrictedElement, GlobalParserTLS, getDefaultParser(), check_docinfo()

+
+
+
+

defusedexpat

+

The defusedexpat package (defusedexpat on PyPI) +comes with binary extensions and a +modified expat library instead of the standard expat parser. It's +basically a stand-alone version of the patches for Python's standard +library C extensions.

+
+

Modifications in expat

+

new definitions:

+
+XML_BOMB_PROTECTION
+XML_DEFAULT_MAX_ENTITY_INDIRECTIONS
+XML_DEFAULT_MAX_ENTITY_EXPANSIONS
+XML_DEFAULT_RESET_DTD
+
+

new XML_FeatureEnum members:

+
+XML_FEATURE_MAX_ENTITY_INDIRECTIONS
+XML_FEATURE_MAX_ENTITY_EXPANSIONS
+XML_FEATURE_IGNORE_DTD
+
+

new XML_Error members:

+
+XML_ERROR_ENTITY_INDIRECTIONS
+XML_ERROR_ENTITY_EXPANSION
+
+

new API functions:

+
+int XML_GetFeature(XML_Parser parser,
+                   enum XML_FeatureEnum feature,
+                   long *value);
+int XML_SetFeature(XML_Parser parser,
+                   enum XML_FeatureEnum feature,
+                   long value);
+int XML_GetFeatureDefault(enum XML_FeatureEnum feature,
+                          long *value);
+int XML_SetFeatureDefault(enum XML_FeatureEnum feature,
+                          long value);
+
+
+
XML_FEATURE_MAX_ENTITY_INDIRECTIONS
+

Limit the amount of indirections that are allowed to occur during the +expansion of a nested entity. A counter starts when an entity reference +is encountered. It resets after the entity is fully expanded. The limit +protects the parser against exponential entity expansion attacks (aka +billion laughs attack). When the limit is exceeded the parser stops and +fails with XML_ERROR_ENTITY_INDIRECTIONS. +A value of 0 disables the protection.

+
+
Supported range
+
0 .. UINT_MAX
+
Default
+
40
+
+
+
XML_FEATURE_MAX_ENTITY_EXPANSIONS
+

Limit the total length of all entity expansions throughout the entire +document. The lengths of all entities are accumulated in a parser variable. +The setting protects against quadratic blowup attacks (lots of expansions +of a large entity declaration). When the sum of all entities exceeds +the limit, the parser stops and fails with XML_ERROR_ENTITY_EXPANSION. +A value of 0 disables the protection.

+
+
Supported range
+
0 .. UINT_MAX
+
Default
+
8 MiB
+
+
+
XML_FEATURE_RESET_DTD
+

Reset all DTD information after the <!DOCTYPE> block has been parsed. When +the flag is set (default: false) all DTD information after the +endDoctypeDeclHandler has been called. The flag can be set inside the +endDoctypeDeclHandler. Without DTD information any entity reference in +the document body leads to XML_ERROR_UNDEFINED_ENTITY.

+
+
Supported range
+
0, 1
+
Default
+
0
+
+
+
+
+
+
+

How to avoid XML vulnerabilities

+
+

Best practices

+
    +
  • Don't allow DTDs
  • +
  • Don't expand entities
  • +
  • Don't resolve externals
  • +
  • Limit parse depth
  • +
  • Limit total input size
  • +
  • Limit parse time
  • +
  • Favor a SAX or iterparse-like parser for potential large data
  • +
  • Validate and properly quote arguments to XSL transformations and +XPath queries
  • +
  • Don't use XPath expression from untrusted sources
  • +
  • Don't apply XSL transformations that come untrusted sources
  • +
+

(based on Brad Hill's Attacking XML Security)

+
+
+
+

Other things to consider

+

XML, XML parsers and processing libraries have more features and possible +issue that could lead to DoS vulnerabilities or security exploits in +applications. I have compiled an incomplete list of theoretical issues that +need further research and more attention. The list is deliberately pessimistic +and a bit paranoid, too. It contains things that might go wrong under daffy +circumstances.

+
+

attribute blowup / hash collision attack

+

XML parsers may use an algorithm with quadratic runtime O(n 2) to +handle attributes and namespaces. If it uses hash tables (dictionaries) to +store attributes and namespaces the implementation may be vulnerable to +hash collision attacks, thus reducing the performance to O(n 2) again. +In either case an attacker is able to forge a denial of service attack with +an XML document that contains thousands upon thousands of attributes in +a single node.

+

I haven't researched yet if expat, pyexpat or libxml2 are vulnerable.

+
+
+

decompression bomb

+

The issue of decompression bombs (aka ZIP bomb) apply to all XML libraries +that can parse compressed XML stream like gzipped HTTP streams or LZMA-ed +files. For an attacker it can reduce the amount of transmitted data by three +magnitudes or more. Gzip is able to compress 1 GiB zeros to roughly 1 MB, +lzma is even better:

+
+$ dd if=/dev/zero bs=1M count=1024 | gzip > zeros.gz
+$ dd if=/dev/zero bs=1M count=1024 | lzma -z > zeros.xy
+$ ls -sh zeros.*
+1020K zeros.gz
+ 148K zeros.xy
+
+

None of Python's standard XML libraries decompress streams except for +xmlrpclib. The module is vulnerable <https://bugs.python.org/issue16043> +to decompression bombs.

+

lxml can load and process compressed data through libxml2 transparently. +libxml2 can handle even very large blobs of compressed data efficiently +without using too much memory. But it doesn't protect applications from +decompression bombs. A carefully written SAX or iterparse-like approach can +be safe.

+
+
+

Processing Instruction

+

PI's like:

+
+<?xml-stylesheet type="text/xsl" href="style.xsl"?>
+
+

may impose more threats for XML processing. It depends if and how a +processor handles processing instructions. The issue of URL retrieval with +network or local file access apply to processing instructions, too.

+
+
+

Other DTD features

+

DTD has more features like <!NOTATION>. I haven't researched how +these features may be a security threat.

+
+
+

XPath

+

XPath statements may introduce DoS vulnerabilities. Code should never execute +queries from untrusted sources. An attacker may also be able to create an XML +document that makes certain XPath queries costly or resource hungry.

+
+
+

XPath injection attacks

+

XPath injeciton attacks pretty much work like SQL injection attacks. +Arguments to XPath queries must be quoted and validated properly, especially +when they are taken from the user. The page Avoid the dangers of XPath injection +list some ramifications of XPath injections.

+

Python's standard library doesn't have XPath support. Lxml supports +parameterized XPath queries which does proper quoting. You just have to use +its xpath() method correctly:

+
+# DON'T
+>>> tree.xpath("/tag[@id='%s']" % value)
+
+# instead do
+>>> tree.xpath("/tag[@id=$tagid]", tagid=name)
+
+
+
+

XInclude

+

XML Inclusion is another way to load and include external files:

+
+<root xmlns:xi="http://www.w3.org/2001/XInclude">
+  <xi:include href="filename.txt" parse="text" />
+</root>
+
+

This feature should be disabled when XML files from an untrusted source are +processed. Some Python XML libraries and libxml2 support XInclude but don't +have an option to sandbox inclusion and limit it to allowed directories.

+
+
+

XMLSchema location

+

A validating XML parser may download schema files from the information in a +xsi:schemaLocation attribute.

+
+<ead xmlns="urn:isbn:1-931666-22-9"
+     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+     xsi:schemaLocation="urn:isbn:1-931666-22-9 http://www.loc.gov/ead/ead.xsd">
+</ead>
+
+
+
+

XSL Transformation

+

You should keep in mind that XSLT is a Turing complete language. Never +process XSLT code from unknown or untrusted source! XSLT processors may +allow you to interact with external resources in ways you can't even imagine. +Some processors even support extensions that allow read/write access to file +system, access to JRE objects or scripting with Jython.

+

Example from Attacking XML Security for Xalan-J:

+
+<xsl:stylesheet version="1.0"
+ xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+ xmlns:rt="http://xml.apache.org/xalan/java/java.lang.Runtime"
+ xmlns:ob="http://xml.apache.org/xalan/java/java.lang.Object"
+ exclude-result-prefixes= "rt ob">
+ <xsl:template match="/">
+   <xsl:variable name="runtimeObject" select="rt:getRuntime()"/>
+   <xsl:variable name="command"
+     select="rt:exec($runtimeObject, &apos;c:\Windows\system32\cmd.exe&apos;)"/>
+   <xsl:variable name="commandAsString" select="ob:toString($command)"/>
+   <xsl:value-of select="$commandAsString"/>
+ </xsl:template>
+</xsl:stylesheet>
+
+
+
+ +
+

Other languages / frameworks

+

Several other programming languages and frameworks are vulnerable as well. A +couple of them are affected by the fact that libxml2 up to 2.9.0 has no +protection against quadratic blowup attacks. Most of them have potential +dangerous default settings for entity expansion and external entities, too.

+
+

Perl

+

Perl's XML::Simple is vulnerable to quadratic entity expansion and external +entity expansion (both local and remote).

+
+
+

Ruby

+

Ruby's REXML document parser is vulnerable to entity expansion attacks +(both quadratic and exponential) but it doesn't do external entity +expansion by default. In order to counteract entity expansion you have to +disable the feature:

+
+REXML::Document.entity_expansion_limit = 0
+
+

libxml-ruby and hpricot don't expand entities in their default configuration.

+
+
+

PHP

+

PHP's SimpleXML API is vulnerable to quadratic entity expansion and loads +entities from local and remote resources. The option LIBXML_NONET disables +network access but still allows local file access. LIBXML_NOENT seems to +have no effect on entity expansion in PHP 5.4.6.

+
+
+

C# / .NET / Mono

+

Information in XML DoS and Defenses (MSDN) suggest that .NET is +vulnerable with its default settings. The article contains code snippets +how to create a secure XML reader:

+
+XmlReaderSettings settings = new XmlReaderSettings();
+settings.ProhibitDtd = false;
+settings.MaxCharactersFromEntities = 1024;
+settings.XmlResolver = null;
+XmlReader reader = XmlReader.Create(stream, settings);
+
+
+
+

Java

+

Untested. The documentation of Xerces and its Xerces SecurityMananger +sounds like Xerces is also vulnerable to billion laugh attacks with its +default settings. It also does entity resolving when an +org.xml.sax.EntityResolver is configured. I'm not yet sure about the +default setting here.

+

Java specialists suggest to have a custom builder factory:

+
+DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
+builderFactory.setXIncludeAware(False);
+builderFactory.setExpandEntityReferences(False);
+builderFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, True);
+# either
+builderFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", True);
+# or if you need DTDs
+builderFactory.setFeature("http://xml.org/sax/features/external-general-entities", False);
+builderFactory.setFeature("http://xml.org/sax/features/external-parameter-entities", False);
+builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", False);
+builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-dtd-grammar", False);
+
+
+
+
+

TODO

+
    +
  • DOM: Use xml.dom.xmlbuilder options for entity handling
  • +
  • SAX: take feature_external_ges and feature_external_pes (?) into account
  • +
  • test experimental monkey patching of stdlib modules
  • +
  • improve documentation
  • +
+
+
+

License

+

Copyright (c) 2013-2017 by Christian Heimes <christian@python.org>

+

Licensed to PSF under a Contributor Agreement.

+

See https://www.python.org/psf/license for licensing details.

+
+
+

Acknowledgements

+
+
Brett Cannon (Python Core developer)
+
review and code cleanup
+
Antoine Pitrou (Python Core developer)
+
code review
+
Aaron Patterson, Ben Murphy and Michael Koziarski (Ruby community)
+
Many thanks to Aaron, Ben and Michael from the Ruby community for their +report and assistance.
+
Thierry Carrez (OpenStack)
+
Many thanks to Thierry for his report to the Python Security Response +Team on behalf of the OpenStack security team.
+
Carl Meyer (Django)
+
Many thanks to Carl for his report to PSRT on behalf of the Django security +team.
+
Daniel Veillard (libxml2)
+
Many thanks to Daniel for his insight and assistance with libxml2.
+
semantics GmbH (https://www.semantics.de/)
+
Many thanks to my employer semantics for letting me work on the issue +during working hours as part of semantics's open source initiative.
+
+
+ +
+

Changelog

+
+

defusedxml 0.7.1

+

Release date: 08-Mar-2021

+
    +
  • Fix regression defusedxml.ElementTree.ParseError (#63) +The ParseError exception is now the same class object as +xml.etree.ElementTree.ParseError again.
  • +
+
+
+

defusedxml 0.7.0

+

Release date: 4-Mar-2021

+
    +
  • No changes
  • +
+
+
+

defusedxml 0.7.0rc2

+

Release date: 12-Jan-2021

+
    +
  • Re-add and deprecate defusedxml.cElementTree
  • +
  • Use GitHub Actions instead of TravisCI
  • +
  • Restore ElementTree attribute of xml.etree module after patching
  • +
+
+
+

defusedxml 0.7.0rc1

+

Release date: 04-May-2020

+
    +
  • Add support for Python 3.9
  • +
  • defusedxml.cElementTree is not available with Python 3.9.
  • +
  • Python 2 is deprecate. Support for Python 2 will be removed in 0.8.0.
  • +
+
+
+

defusedxml 0.6.0

+

Release date: 17-Apr-2019

+
    +
  • Increase test coverage.
  • +
  • Add badges to README.
  • +
+
+
+

defusedxml 0.6.0rc1

+

Release date: 14-Apr-2019

+
    +
  • Test on Python 3.7 stable and 3.8-dev
  • +
  • Drop support for Python 3.4
  • +
  • No longer pass html argument to XMLParse. It has been deprecated and +ignored for a long time. The DefusedXMLParser still takes a html argument. +A deprecation warning is issued when the argument is False and a TypeError +when it's True.
  • +
  • defusedxml now fails early when pyexpat stdlib module is not available or +broken.
  • +
  • defusedxml.ElementTree.__all__ now lists ParseError as public attribute.
  • +
  • The defusedxml.ElementTree and defusedxml.cElementTree modules had a typo +and used XMLParse instead of XMLParser as an alias for DefusedXMLParser. +Both the old and fixed name are now available.
  • +
+
+
+

defusedxml 0.5.0

+

Release date: 07-Feb-2017

+
    +
  • No changes
  • +
+
+
+

defusedxml 0.5.0.rc1

+

Release date: 28-Jan-2017

+
    +
  • Add compatibility with Python 3.6
  • +
  • Drop support for Python 2.6, 3.1, 3.2, 3.3
  • +
  • Fix lxml tests (XMLSyntaxError: Detected an entity reference loop)
  • +
+
+
+

defusedxml 0.4.1

+

Release date: 28-Mar-2013

+
    +
  • Add more demo exploits, e.g. python_external.py and Xalan XSLT demos.
  • +
  • Improved documentation.
  • +
+
+
+

defusedxml 0.4

+

Release date: 25-Feb-2013

+
    +
  • As per http://seclists.org/oss-sec/2013/q1/340 please REJECT +CVE-2013-0278, CVE-2013-0279 and CVE-2013-0280 and use CVE-2013-1664, +CVE-2013-1665 for OpenStack/etc.
  • +
  • Add missing parser_list argument to sax.make_parser(). The argument is +ignored, though. (thanks to Florian Apolloner)
  • +
  • Add demo exploit for external entity attack on Python's SAX parser, XML-RPC +and WebDAV.
  • +
+
+
+

defusedxml 0.3

+

Release date: 19-Feb-2013

+
    +
  • Improve documentation
  • +
+
+
+

defusedxml 0.2

+

Release date: 15-Feb-2013

+
    +
  • Rename ExternalEntitiesForbidden to ExternalReferenceForbidden
  • +
  • Rename defusedxml.lxml.check_dtd() to check_docinfo()
  • +
  • Unify argument names in callbacks
  • +
  • Add arguments and formatted representation to exceptions
  • +
  • Add forbid_external argument to all functions and classes
  • +
  • More tests
  • +
  • LOTS of documentation
  • +
  • Add example code for other languages (Ruby, Perl, PHP) and parsers (Genshi)
  • +
  • Add protection against XML and gzip attacks to xmlrpclib
  • +
+
+
+

defusedxml 0.1

+

Release date: 08-Feb-2013

+
    +
  • Initial and internal release for PSRT review
  • +
+
+
+
+ + diff -Nru defusedxml-0.7.1/debian/changelog defusedxml-0.7.1/debian/changelog --- defusedxml-0.7.1/debian/changelog 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/changelog 2024-03-17 09:20:42.000000000 +0000 @@ -1,120 +1,11 @@ -defusedxml (0.7.1-2) unstable; urgency=medium +defusedxml (0.7.1-1ppa1~noble) noble; urgency=low - [ Debian Janitor ] - * Set upstream metadata fields: Contact, Security-Contact. - * Update standards version to 4.6.1, no changes needed. - * Set field Upstream-Contact in debian/copyright. - * Remove obsolete field Contact from debian/upstream/metadata (already present - in machine-readable debian/copyright). + * Modifications for PPA release. - -- Jelmer Vernooij Sun, 16 Oct 2022 23:26:00 +0100 + -- Joachim Metz Sun, 17 Mar 2024 10:20:42 +0100 -defusedxml (0.7.1-1) unstable; urgency=medium +defusedxml (0.7.1-1) unstable; urgency=low - * Team upload. + * Auto-generated - [ Ondřej Nový ] - * d/control: Update Maintainer field with new Debian Python Team - contact address. - * d/control: Update Vcs-* fields with new Debian Python Team Salsa - layout. - - [ Debian Janitor ] - * Set upstream metadata fields: Bug-Submit. - * Update standards version to 4.5.0, no changes needed. - * Bump debhelper from old 12 to 13. - + Drop check for DEB_BUILD_OPTIONS containing "nocheck", since debhelper now - does this. - * Update standards version to 4.5.1, no changes needed. - - [ Gordon Ball ] - * d/watch: use github as upstream, drop expired signing key - * New upstream version 0.7.1 - * Rebase patches, drop all - * Update homepage to github.com/tiran/defusedxml - * Rules-requires-root: no - * docs: drop (generated) README.html - * Standards-Version: 4.6.0 - * Add autopkgtest - - -- Gordon Ball Tue, 12 Oct 2021 17:52:18 +0000 - -defusedxml (0.6.0-2) unstable; urgency=medium - - [ Ondřej Nový ] - * Bump Standards-Version to 4.4.1. - - [ Debian Janitor ] - * Remove obsolete fields Name from debian/upstream/metadata. - * Set upstream metadata fields: Bug-Database, Repository. - - [ Sandro Tosi ] - * Drop python2 support; Closes: #942945, #936382 - - -- Sandro Tosi Wed, 19 Feb 2020 18:38:19 -0500 - -defusedxml (0.6.0-1) unstable; urgency=medium - - * Team upload. - - [ Ondřej Nový ] - * Use debhelper-compat instead of debian/compat. - - [ William Grzybowski ] - * New upstream version 0.6.0 - * d/control: add autopkgtest-pkg-python Testsuite - * d/control: update debhelper to version 12. - * d/control: update Standards-Version to 4.4.0 (No changes needed) - * d/copyright: fix copyright authors and years for upstream and debian - * d/patches: add patch to remove images avoiding possible privacy breach - * d/salsa-ci.yml: add to run CI in Salsa - - -- William Grzybowski Tue, 23 Jul 2019 19:53:42 -0300 - -defusedxml (0.5.0-2) unstable; urgency=medium - - [ Ondřej Nový ] - * d/control: Set Vcs-* to salsa.debian.org - * d/copyright: Use https protocol in Format field - * d/changelog: Remove trailing whitespaces - * d/control: Remove ancient X-Python-Version field - * d/control: Remove ancient X-Python3-Version field - * Convert git repository from git-dpm to gbp layout - - [ Jelmer Vernooij ] - * Bump debhelper from old 9 to 10. - * Re-export upstream signing key without extra signatures. - * Add a basic debian/upstream/metadata. - - -- Jelmer Vernooij Tue, 13 Feb 2018 10:18:18 +0100 - -defusedxml (0.5.0-1) unstable; urgency=medium - - [ Ondřej Nový ] - * Fixed VCS URL (https) - - [ Jelmer Vernooij ] - * Bump standards version (no changes). - * Bump debhelper version to 9. - * Refresh upstream signing key (new subkeys). - * debian/watch: properly handle RC releases. - * New upstream release. - * Add myself to uploaders. - * Run tests during build. - - -- Jelmer Vernooij Sun, 02 Jul 2017 14:19:56 +0000 - -defusedxml (0.4.1-2) unstable; urgency=medium - - * Added Python 3 support. - * Bumped Standards-Version to 3.9.5 (no changes needed) - * Updated VCS-* fields to canonical locations. - * Added watch file. - - -- Nikolaus Rath Sun, 29 Jun 2014 16:38:39 -0700 - -defusedxml (0.4.1-1) unstable; urgency=low - - * Initial release. (Closes: #705691) - - -- Luke Faraone Thu, 18 Apr 2013 11:15:53 -0400 + -- log2timeline development team Sun, 17 Mar 2024 10:20:42 -0100 diff -Nru defusedxml-0.7.1/debian/clean defusedxml-0.7.1/debian/clean --- defusedxml-0.7.1/debian/clean 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/debian/clean 2024-03-17 09:20:42.000000000 +0000 @@ -0,0 +1,2 @@ +defusedxml/*.pyc +*.pyc diff -Nru defusedxml-0.7.1/debian/compat defusedxml-0.7.1/debian/compat --- defusedxml-0.7.1/debian/compat 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/debian/compat 2024-03-17 09:20:42.000000000 +0000 @@ -0,0 +1 @@ +10 diff -Nru defusedxml-0.7.1/debian/control defusedxml-0.7.1/debian/control --- defusedxml-0.7.1/debian/control 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/control 2024-03-17 09:20:42.000000000 +0000 @@ -1,29 +1,14 @@ Source: defusedxml -Maintainer: Debian Python Team -Uploaders: Luke Faraone , Jelmer Vernooij Section: python -Priority: optional -Build-Depends: dh-python, - python3-all, - debhelper-compat (= 13), - python3-setuptools -Standards-Version: 4.6.1 +Priority: extra +Maintainer: Christian Heimes +Build-Depends: debhelper (>= 9), dh-python, python3-all (>= 3.6~), python3-setuptools +Standards-Version: 4.1.4 +X-Python3-Version: >= 3.6 Homepage: https://github.com/tiran/defusedxml -Testsuite: autopkgtest-pkg-python -Vcs-Git: https://salsa.debian.org/python-team/packages/defusedxml.git -Vcs-Browser: https://salsa.debian.org/python-team/packages/defusedxml -Rules-Requires-Root: no Package: python3-defusedxml Architecture: all -Depends: ${misc:Depends}, ${python3:Depends} -Description: XML bomb protection for Python stdlib modules (for Python 3) - The results of an attack on a vulnerable XML library can be fairly dramatic. - With just a few hundred bytes of XML data an attacker can occupy several - gigabytes of memory within seconds. An attacker can also keep - CPUs busy for a long time with a small to medium size request. - . - This library allows for XML to be parsed in a manner that avoids these - pitfalls. - . - This package contains the module for the Python 3 interpreter. +Depends: ${python3:Depends}, ${misc:Depends} +Description: XML bomb protection for Python stdlib modules + XML bomb protection for Python stdlib modules diff -Nru defusedxml-0.7.1/debian/copyright defusedxml-0.7.1/debian/copyright --- defusedxml-0.7.1/debian/copyright 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/copyright 2024-03-17 09:20:42.000000000 +0000 @@ -1,66 +1,49 @@ -Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/ -Upstream-Name: defusedxml -Source: https://github.com/tiran/defusedxml -Upstream-Contact: Christian Heimes - -Files: * -Copyright: 2013-2019 Christian Heimes -License: Python - -Files: debian/* -Copyright: 2013 Luke Faraone - 2014 Nikolaus Rath - 2017-2018 Jelmer Vernooij - 2017-2019 Ondřej Nový - 2019 William Grzybowski -License: Python - -License: Python - PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2 - -------------------------------------------- - . - 1. This LICENSE AGREEMENT is between the Python Software Foundation - ("PSF"), and the Individual or Organization ("Licensee") accessing and - otherwise using this software ("Python") in source or binary form and - its associated documentation. - . - 2. Subject to the terms and conditions of this License Agreement, PSF - hereby grants Licensee a nonexclusive, royalty-free, world-wide - license to reproduce, analyze, test, perform and/or display publicly, - prepare derivative works, distribute, and otherwise use Python - alone or in any derivative version, provided, however, that PSF's - License Agreement and PSF's notice of copyright, i.e., "Copyright (c) - 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Python Software Foundation; - All Rights Reserved" are retained in Python alone or in any derivative - version prepared by Licensee. - . - 3. In the event Licensee prepares a derivative work that is based on - or incorporates Python or any part thereof, and wants to make - the derivative work available to others as provided herein, then - Licensee hereby agrees to include in any such work a brief summary of - the changes made to Python. - . - 4. PSF is making Python available to Licensee on an "AS IS" - basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR - IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND - DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS - FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT - INFRINGE ANY THIRD PARTY RIGHTS. - . - 5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON - FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS - A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON, - OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. - . - 6. This License Agreement will automatically terminate upon a material - breach of its terms and conditions. - . - 7. Nothing in this License Agreement shall be deemed to create any - relationship of agency, partnership, or joint venture between PSF and - Licensee. This License Agreement does not grant permission to use PSF - trademarks or trade name in a trademark sense to endorse or promote - products or services of Licensee, or any third party. - . - 8. By copying, installing or otherwise using Python, Licensee - agrees to be bound by the terms and conditions of this License - Agreement. +PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2 +-------------------------------------------- + +1. This LICENSE AGREEMENT is between the Python Software Foundation +("PSF"), and the Individual or Organization ("Licensee") accessing and +otherwise using this software ("Python") in source or binary form and +its associated documentation. + +2. Subject to the terms and conditions of this License Agreement, PSF +hereby grants Licensee a nonexclusive, royalty-free, world-wide +license to reproduce, analyze, test, perform and/or display publicly, +prepare derivative works, distribute, and otherwise use Python +alone or in any derivative version, provided, however, that PSF's +License Agreement and PSF's notice of copyright, i.e., "Copyright (c) +2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Python Software Foundation; +All Rights Reserved" are retained in Python alone or in any derivative +version prepared by Licensee. + +3. In the event Licensee prepares a derivative work that is based on +or incorporates Python or any part thereof, and wants to make +the derivative work available to others as provided herein, then +Licensee hereby agrees to include in any such work a brief summary of +the changes made to Python. + +4. PSF is making Python available to Licensee on an "AS IS" +basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR +IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND +DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS +FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT +INFRINGE ANY THIRD PARTY RIGHTS. + +5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON +FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS +A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON, +OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. + +6. This License Agreement will automatically terminate upon a material +breach of its terms and conditions. + +7. Nothing in this License Agreement shall be deemed to create any +relationship of agency, partnership, or joint venture between PSF and +Licensee. This License Agreement does not grant permission to use PSF +trademarks or trade name in a trademark sense to endorse or promote +products or services of Licensee, or any third party. + +8. By copying, installing or otherwise using Python, Licensee +agrees to be bound by the terms and conditions of this License +Agreement. + diff -Nru defusedxml-0.7.1/debian/docs defusedxml-0.7.1/debian/docs --- defusedxml-0.7.1/debian/docs 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/docs 1970-01-01 00:00:00.000000000 +0000 @@ -1,2 +0,0 @@ -README.txt -README.md diff -Nru defusedxml-0.7.1/debian/rules defusedxml-0.7.1/debian/rules --- defusedxml-0.7.1/debian/rules 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/rules 2024-03-17 09:20:42.000000000 +0000 @@ -1,11 +1,8 @@ #!/usr/bin/make -f -export PYBUILD_NAME=defusedxml - %: - dh $@ --with python3 --buildsystem=pybuild + dh $@ --buildsystem=pybuild --with=python3 +.PHONY: override_dh_auto_test override_dh_auto_test: - for PYTHON in $(shell py3versions -r); do\ - $$PYTHON ./tests.py; \ - done + diff -Nru defusedxml-0.7.1/debian/salsa-ci.yml defusedxml-0.7.1/debian/salsa-ci.yml --- defusedxml-0.7.1/debian/salsa-ci.yml 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/salsa-ci.yml 1970-01-01 00:00:00.000000000 +0000 @@ -1,4 +0,0 @@ ---- -include: - - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/salsa-ci.yml - - https://salsa.debian.org/salsa-ci-team/pipeline/raw/master/pipeline-jobs.yml diff -Nru defusedxml-0.7.1/debian/source/options defusedxml-0.7.1/debian/source/options --- defusedxml-0.7.1/debian/source/options 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/debian/source/options 2024-03-17 09:20:42.000000000 +0000 @@ -0,0 +1 @@ +extend-diff-ignore = "(^|/)(\.eggs|config\.h|config\.log|config\.status|.*\.egg-info|.*\.egg-info/.*|.*\.pxd|.*\.pyx|Makefile|CMakeCache.txt|CMakeFiles.*)$" diff -Nru defusedxml-0.7.1/debian/tests/control defusedxml-0.7.1/debian/tests/control --- defusedxml-0.7.1/debian/tests/control 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/tests/control 1970-01-01 00:00:00.000000000 +0000 @@ -1,3 +0,0 @@ -Test-Command: cp -r tests.py xmltestdata $AUTOPKGTEST_TMP && cd $AUTOPKGTEST_TMP && for py3 in $(py3versions -s); do $py3 tests.py; done -Depends: @, python3-all -Restrictions: allow-stderr diff -Nru defusedxml-0.7.1/debian/upstream/metadata defusedxml-0.7.1/debian/upstream/metadata --- defusedxml-0.7.1/debian/upstream/metadata 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/upstream/metadata 1970-01-01 00:00:00.000000000 +0000 @@ -1,5 +0,0 @@ -Bug-Submit: https://github.com/tiran/defusedxml/issues/new -Repository: https://github.com/tiran/defusedxml.git -Repository-Browse: https://github.com/tiran/defusedxml -Bug-Database: https://github.com/tiran/defusedxml/issues -Security-Contact: https://github.com/tiran/defusedxml/tree/HEAD/SECURITY.md diff -Nru defusedxml-0.7.1/debian/watch defusedxml-0.7.1/debian/watch --- defusedxml-0.7.1/debian/watch 2022-10-16 22:26:00.000000000 +0000 +++ defusedxml-0.7.1/debian/watch 1970-01-01 00:00:00.000000000 +0000 @@ -1,3 +0,0 @@ -version=4 -opts=uversionmangle=s/(\d)[_\.\-\+]?((rc)\d*)$/$1~$2/ \ - https://github.com/tiran/defusedxml/tags .*/v?@ANY_VERSION@@ARCHIVE_EXT@ diff -Nru defusedxml-0.7.1/defusedxml.egg-info/PKG-INFO defusedxml-0.7.1/defusedxml.egg-info/PKG-INFO --- defusedxml-0.7.1/defusedxml.egg-info/PKG-INFO 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/defusedxml.egg-info/PKG-INFO 2021-03-08 10:59:07.000000000 +0000 @@ -0,0 +1,976 @@ +Metadata-Version: 1.2 +Name: defusedxml +Version: 0.7.1 +Summary: XML bomb protection for Python stdlib modules +Home-page: https://github.com/tiran/defusedxml +Author: Christian Heimes +Author-email: christian@python.org +Maintainer: Christian Heimes +Maintainer-email: christian@python.org +License: PSFL +Download-URL: https://pypi.python.org/pypi/defusedxml +Description: =================================================== + defusedxml -- defusing XML bombs and other exploits + =================================================== + + .. image:: https://img.shields.io/pypi/v/defusedxml.svg + :target: https://pypi.org/project/defusedxml/ + :alt: Latest Version + + .. image:: https://img.shields.io/pypi/pyversions/defusedxml.svg + :target: https://pypi.org/project/defusedxml/ + :alt: Supported Python versions + + .. image:: https://travis-ci.org/tiran/defusedxml.svg?branch=master + :target: https://travis-ci.org/tiran/defusedxml + :alt: Travis CI + + .. image:: https://codecov.io/github/tiran/defusedxml/coverage.svg?branch=master + :target: https://codecov.io/github/tiran/defusedxml?branch=master + :alt: codecov + + .. image:: https://img.shields.io/pypi/dm/defusedxml.svg + :target: https://pypistats.org/packages/defusedxml + :alt: PyPI downloads + + .. image:: https://img.shields.io/badge/code%20style-black-000000.svg + :target: https://github.com/psf/black + :alt: Code style: black + + .. + + "It's just XML, what could probably go wrong?" + + Christian Heimes + + Synopsis + ======== + + The results of an attack on a vulnerable XML library can be fairly dramatic. + With just a few hundred **Bytes** of XML data an attacker can occupy several + **Gigabytes** of memory within **seconds**. An attacker can also keep + CPUs busy for a long time with a small to medium size request. Under some + circumstances it is even possible to access local files on your + server, to circumvent a firewall, or to abuse services to rebound attacks to + third parties. + + The attacks use and abuse less common features of XML and its parsers. The + majority of developers are unacquainted with features such as processing + instructions and entity expansions that XML inherited from SGML. At best + they know about ```` from experience with HTML but they are not + aware that a document type definition (DTD) can generate an HTTP request + or load a file from the file system. + + None of the issues is new. They have been known for a long time. Billion + laughs was first reported in 2003. Nevertheless some XML libraries and + applications are still vulnerable and even heavy users of XML are + surprised by these features. It's hard to say whom to blame for the + situation. It's too short sighted to shift all blame on XML parsers and + XML libraries for using insecure default settings. After all they + properly implement XML specifications. Application developers must not rely + that a library is always configured for security and potential harmful data + by default. + + + .. contents:: Table of Contents + :depth: 2 + + + Attack vectors + ============== + + billion laughs / exponential entity expansion + --------------------------------------------- + + The `Billion Laughs`_ attack -- also known as exponential entity expansion -- + uses multiple levels of nested entities. The original example uses 9 levels + of 10 expansions in each level to expand the string ``lol`` to a string of + 3 * 10 :sup:`9` bytes, hence the name "billion laughs". The resulting string + occupies 3 GB (2.79 GiB) of memory; intermediate strings require additional + memory. Because most parsers don't cache the intermediate step for every + expansion it is repeated over and over again. It increases the CPU load even + more. + + An XML document of just a few hundred bytes can disrupt all services on a + machine within seconds. + + Example XML:: + + + + + + ]> + &d; + + + quadratic blowup entity expansion + --------------------------------- + + A quadratic blowup attack is similar to a `Billion Laughs`_ attack; it abuses + entity expansion, too. Instead of nested entities it repeats one large entity + with a couple of thousand chars over and over again. The attack isn't as + efficient as the exponential case but it avoids triggering countermeasures of + parsers against heavily nested entities. Some parsers limit the depth and + breadth of a single entity but not the total amount of expanded text + throughout an entire XML document. + + A medium-sized XML document with a couple of hundred kilobytes can require a + couple of hundred MB to several GB of memory. When the attack is combined + with some level of nested expansion an attacker is able to achieve a higher + ratio of success. + + :: + + + ]> + &a;&a;&a;... repeat + + + external entity expansion (remote) + ---------------------------------- + + Entity declarations can contain more than just text for replacement. They can + also point to external resources by public identifiers or system identifiers. + System identifiers are standard URIs. When the URI is a URL (e.g. a + ``http://`` locator) some parsers download the resource from the remote + location and embed them into the XML document verbatim. + + Simple example of a parsed external entity:: + + + ]> + + + The case of parsed external entities works only for valid XML content. The + XML standard also supports unparsed external entities with a + ``NData declaration``. + + External entity expansion opens the door to plenty of exploits. An attacker + can abuse a vulnerable XML library and application to rebound and forward + network requests with the IP address of the server. It highly depends + on the parser and the application what kind of exploit is possible. For + example: + + * An attacker can circumvent firewalls and gain access to restricted + resources as all the requests are made from an internal and trustworthy + IP address, not from the outside. + * An attacker can abuse a service to attack, spy on or DoS your servers but + also third party services. The attack is disguised with the IP address of + the server and the attacker is able to utilize the high bandwidth of a big + machine. + * An attacker can exhaust additional resources on the machine, e.g. with + requests to a service that doesn't respond or responds with very large + files. + * An attacker may gain knowledge, when, how often and from which IP address + an XML document is accessed. + * An attacker could send mail from inside your network if the URL handler + supports ``smtp://`` URIs. + + + external entity expansion (local file) + -------------------------------------- + + External entities with references to local files are a sub-case of external + entity expansion. It's listed as an extra attack because it deserves extra + attention. Some XML libraries such as lxml disable network access by default + but still allow entity expansion with local file access by default. Local + files are either referenced with a ``file://`` URL or by a file path (either + relative or absolute). + + An attacker may be able to access and download all files that can be read by + the application process. This may include critical configuration files, too. + + :: + + + ]> + + + + DTD retrieval + ------------- + + This case is similar to external entity expansion, too. Some XML libraries + like Python's xml.dom.pulldom retrieve document type definitions from remote + or local locations. Several attack scenarios from the external entity case + apply to this issue as well. + + :: + + + + + + text + + + + Python XML Libraries + ==================== + + .. csv-table:: vulnerabilities and features + :header: "kind", "sax", "etree", "minidom", "pulldom", "xmlrpc", "lxml", "genshi" + :widths: 24, 7, 8, 8, 7, 8, 8, 8 + :stub-columns: 0 + + "billion laughs", "**True**", "**True**", "**True**", "**True**", "**True**", "False (1)", "False (5)" + "quadratic blowup", "**True**", "**True**", "**True**", "**True**", "**True**", "**True**", "False (5)" + "external entity expansion (remote)", "**True**", "False (3)", "False (4)", "**True**", "false", "False (1)", "False (5)" + "external entity expansion (local file)", "**True**", "False (3)", "False (4)", "**True**", "false", "**True**", "False (5)" + "DTD retrieval", "**True**", "False", "False", "**True**", "false", "False (1)", "False" + "gzip bomb", "False", "False", "False", "False", "**True**", "**partly** (2)", "False" + "xpath support (7)", "False", "False", "False", "False", "False", "**True**", "False" + "xsl(t) support (7)", "False", "False", "False", "False", "False", "**True**", "False" + "xinclude support (7)", "False", "**True** (6)", "False", "False", "False", "**True** (6)", "**True**" + "C library", "expat", "expat", "expat", "expat", "expat", "libxml2", "expat" + + 1. Lxml is protected against billion laughs attacks and doesn't do network + lookups by default. + 2. libxml2 and lxml are not directly vulnerable to gzip decompression bombs + but they don't protect you against them either. + 3. xml.etree doesn't expand entities and raises a ParserError when an entity + occurs. + 4. minidom doesn't expand entities and simply returns the unexpanded entity + verbatim. + 5. genshi.input of genshi 0.6 doesn't support entity expansion and raises a + ParserError when an entity occurs. + 6. Library has (limited) XInclude support but requires an additional step to + process inclusion. + 7. These are features but they may introduce exploitable holes, see + `Other things to consider`_ + + + Settings in standard library + ---------------------------- + + + xml.sax.handler Features + ........................ + + feature_external_ges (http://xml.org/sax/features/external-general-entities) + disables external entity expansion + + feature_external_pes (http://xml.org/sax/features/external-parameter-entities) + the option is ignored and doesn't modify any functionality + + DOM xml.dom.xmlbuilder.Options + .............................. + + external_parameter_entities + ignored + + external_general_entities + ignored + + external_dtd_subset + ignored + + entities + unsure + + + defusedxml + ========== + + The `defusedxml package`_ (`defusedxml on PyPI`_) + contains several Python-only workarounds and fixes + for denial of service and other vulnerabilities in Python's XML libraries. + In order to benefit from the protection you just have to import and use the + listed functions / classes from the right defusedxml module instead of the + original module. Merely `defusedxml.xmlrpc`_ is implemented as monkey patch. + + Instead of:: + + >>> from xml.etree.ElementTree import parse + >>> et = parse(xmlfile) + + alter code to:: + + >>> from defusedxml.ElementTree import parse + >>> et = parse(xmlfile) + + Additionally the package has an **untested** function to monkey patch + all stdlib modules with ``defusedxml.defuse_stdlib()``. + + All functions and parser classes accept three additional keyword arguments. + They return either the same objects as the original functions or compatible + subclasses. + + forbid_dtd (default: False) + disallow XML with a ```` processing instruction and raise a + *DTDForbidden* exception when a DTD processing instruction is found. + + forbid_entities (default: True) + disallow XML with ```` declarations inside the DTD and raise an + *EntitiesForbidden* exception when an entity is declared. + + forbid_external (default: True) + disallow any access to remote or local resources in external entities + or DTD and raising an *ExternalReferenceForbidden* exception when a DTD + or entity references an external resource. + + + defusedxml (package) + -------------------- + + DefusedXmlException, DTDForbidden, EntitiesForbidden, + ExternalReferenceForbidden, NotSupportedError + + defuse_stdlib() (*experimental*) + + + defusedxml.cElementTree + ----------------------- + + **NOTE** ``defusedxml.cElementTree`` is deprecated and will be removed in a + future release. Import from ``defusedxml.ElementTree`` instead. + + parse(), iterparse(), fromstring(), XMLParser + + + defusedxml.ElementTree + ----------------------- + + parse(), iterparse(), fromstring(), XMLParser + + + defusedxml.expatreader + ---------------------- + + create_parser(), DefusedExpatParser + + + defusedxml.sax + -------------- + + parse(), parseString(), make_parser() + + + defusedxml.expatbuilder + ----------------------- + + parse(), parseString(), DefusedExpatBuilder, DefusedExpatBuilderNS + + + defusedxml.minidom + ------------------ + + parse(), parseString() + + + defusedxml.pulldom + ------------------ + + parse(), parseString() + + + defusedxml.xmlrpc + ----------------- + + The fix is implemented as monkey patch for the stdlib's xmlrpc package (3.x) + or xmlrpclib module (2.x). The function `monkey_patch()` enables the fixes, + `unmonkey_patch()` removes the patch and puts the code in its former state. + + The monkey patch protects against XML related attacks as well as + decompression bombs and excessively large requests or responses. The default + setting is 30 MB for requests, responses and gzip decompression. You can + modify the default by changing the module variable `MAX_DATA`. A value of + `-1` disables the limit. + + + defusedxml.lxml + --------------- + + **DEPRECATED** The module is deprecated and will be removed in a future + release. + + The module acts as an *example* how you could protect code that uses + lxml.etree. It implements a custom Element class that filters out + Entity instances, a custom parser factory and a thread local storage for + parser instances. It also has a check_docinfo() function which inspects + a tree for internal or external DTDs and entity declarations. In order to + check for entities lxml > 3.0 is required. + + parse(), fromstring() + RestrictedElement, GlobalParserTLS, getDefaultParser(), check_docinfo() + + + defusedexpat + ============ + + The `defusedexpat package`_ (`defusedexpat on PyPI`_) + comes with binary extensions and a + `modified expat`_ library instead of the standard `expat parser`_. It's + basically a stand-alone version of the patches for Python's standard + library C extensions. + + Modifications in expat + ---------------------- + + new definitions:: + + XML_BOMB_PROTECTION + XML_DEFAULT_MAX_ENTITY_INDIRECTIONS + XML_DEFAULT_MAX_ENTITY_EXPANSIONS + XML_DEFAULT_RESET_DTD + + new XML_FeatureEnum members:: + + XML_FEATURE_MAX_ENTITY_INDIRECTIONS + XML_FEATURE_MAX_ENTITY_EXPANSIONS + XML_FEATURE_IGNORE_DTD + + new XML_Error members:: + + XML_ERROR_ENTITY_INDIRECTIONS + XML_ERROR_ENTITY_EXPANSION + + new API functions:: + + int XML_GetFeature(XML_Parser parser, + enum XML_FeatureEnum feature, + long *value); + int XML_SetFeature(XML_Parser parser, + enum XML_FeatureEnum feature, + long value); + int XML_GetFeatureDefault(enum XML_FeatureEnum feature, + long *value); + int XML_SetFeatureDefault(enum XML_FeatureEnum feature, + long value); + + XML_FEATURE_MAX_ENTITY_INDIRECTIONS + Limit the amount of indirections that are allowed to occur during the + expansion of a nested entity. A counter starts when an entity reference + is encountered. It resets after the entity is fully expanded. The limit + protects the parser against exponential entity expansion attacks (aka + billion laughs attack). When the limit is exceeded the parser stops and + fails with `XML_ERROR_ENTITY_INDIRECTIONS`. + A value of 0 disables the protection. + + Supported range + 0 .. UINT_MAX + Default + 40 + + XML_FEATURE_MAX_ENTITY_EXPANSIONS + Limit the total length of all entity expansions throughout the entire + document. The lengths of all entities are accumulated in a parser variable. + The setting protects against quadratic blowup attacks (lots of expansions + of a large entity declaration). When the sum of all entities exceeds + the limit, the parser stops and fails with `XML_ERROR_ENTITY_EXPANSION`. + A value of 0 disables the protection. + + Supported range + 0 .. UINT_MAX + Default + 8 MiB + + XML_FEATURE_RESET_DTD + Reset all DTD information after the block has been parsed. When + the flag is set (default: false) all DTD information after the + endDoctypeDeclHandler has been called. The flag can be set inside the + endDoctypeDeclHandler. Without DTD information any entity reference in + the document body leads to `XML_ERROR_UNDEFINED_ENTITY`. + + Supported range + 0, 1 + Default + 0 + + + How to avoid XML vulnerabilities + ================================ + + Best practices + -------------- + + * Don't allow DTDs + * Don't expand entities + * Don't resolve externals + * Limit parse depth + * Limit total input size + * Limit parse time + * Favor a SAX or iterparse-like parser for potential large data + * Validate and properly quote arguments to XSL transformations and + XPath queries + * Don't use XPath expression from untrusted sources + * Don't apply XSL transformations that come untrusted sources + + (based on Brad Hill's `Attacking XML Security`_) + + + Other things to consider + ======================== + + XML, XML parsers and processing libraries have more features and possible + issue that could lead to DoS vulnerabilities or security exploits in + applications. I have compiled an incomplete list of theoretical issues that + need further research and more attention. The list is deliberately pessimistic + and a bit paranoid, too. It contains things that might go wrong under daffy + circumstances. + + + attribute blowup / hash collision attack + ---------------------------------------- + + XML parsers may use an algorithm with quadratic runtime O(n :sup:`2`) to + handle attributes and namespaces. If it uses hash tables (dictionaries) to + store attributes and namespaces the implementation may be vulnerable to + hash collision attacks, thus reducing the performance to O(n :sup:`2`) again. + In either case an attacker is able to forge a denial of service attack with + an XML document that contains thousands upon thousands of attributes in + a single node. + + I haven't researched yet if expat, pyexpat or libxml2 are vulnerable. + + + decompression bomb + ------------------ + + The issue of decompression bombs (aka `ZIP bomb`_) apply to all XML libraries + that can parse compressed XML stream like gzipped HTTP streams or LZMA-ed + files. For an attacker it can reduce the amount of transmitted data by three + magnitudes or more. Gzip is able to compress 1 GiB zeros to roughly 1 MB, + lzma is even better:: + + $ dd if=/dev/zero bs=1M count=1024 | gzip > zeros.gz + $ dd if=/dev/zero bs=1M count=1024 | lzma -z > zeros.xy + $ ls -sh zeros.* + 1020K zeros.gz + 148K zeros.xy + + None of Python's standard XML libraries decompress streams except for + ``xmlrpclib``. The module is vulnerable + to decompression bombs. + + lxml can load and process compressed data through libxml2 transparently. + libxml2 can handle even very large blobs of compressed data efficiently + without using too much memory. But it doesn't protect applications from + decompression bombs. A carefully written SAX or iterparse-like approach can + be safe. + + + Processing Instruction + ---------------------- + + `PI`_'s like:: + + + + may impose more threats for XML processing. It depends if and how a + processor handles processing instructions. The issue of URL retrieval with + network or local file access apply to processing instructions, too. + + + Other DTD features + ------------------ + + `DTD`_ has more features like ````. I haven't researched how + these features may be a security threat. + + + XPath + ----- + + XPath statements may introduce DoS vulnerabilities. Code should never execute + queries from untrusted sources. An attacker may also be able to create an XML + document that makes certain XPath queries costly or resource hungry. + + + XPath injection attacks + ----------------------- + + XPath injeciton attacks pretty much work like SQL injection attacks. + Arguments to XPath queries must be quoted and validated properly, especially + when they are taken from the user. The page `Avoid the dangers of XPath injection`_ + list some ramifications of XPath injections. + + Python's standard library doesn't have XPath support. Lxml supports + parameterized XPath queries which does proper quoting. You just have to use + its xpath() method correctly:: + + # DON'T + >>> tree.xpath("/tag[@id='%s']" % value) + + # instead do + >>> tree.xpath("/tag[@id=$tagid]", tagid=name) + + + XInclude + -------- + + `XML Inclusion`_ is another way to load and include external files:: + + + + + + This feature should be disabled when XML files from an untrusted source are + processed. Some Python XML libraries and libxml2 support XInclude but don't + have an option to sandbox inclusion and limit it to allowed directories. + + + XMLSchema location + ------------------ + + A validating XML parser may download schema files from the information in a + ``xsi:schemaLocation`` attribute. + + :: + + + + + + XSL Transformation + ------------------ + + You should keep in mind that XSLT is a Turing complete language. Never + process XSLT code from unknown or untrusted source! XSLT processors may + allow you to interact with external resources in ways you can't even imagine. + Some processors even support extensions that allow read/write access to file + system, access to JRE objects or scripting with Jython. + + Example from `Attacking XML Security`_ for Xalan-J:: + + + + + + + + + + + + Related CVEs + ============ + + CVE-2013-1664 + Unrestricted entity expansion induces DoS vulnerabilities in Python XML + libraries (XML bomb) + + CVE-2013-1665 + External entity expansion in Python XML libraries inflicts potential + security flaws and DoS vulnerabilities + + + Other languages / frameworks + ============================= + + Several other programming languages and frameworks are vulnerable as well. A + couple of them are affected by the fact that libxml2 up to 2.9.0 has no + protection against quadratic blowup attacks. Most of them have potential + dangerous default settings for entity expansion and external entities, too. + + Perl + ---- + + Perl's XML::Simple is vulnerable to quadratic entity expansion and external + entity expansion (both local and remote). + + + Ruby + ---- + + Ruby's REXML document parser is vulnerable to entity expansion attacks + (both quadratic and exponential) but it doesn't do external entity + expansion by default. In order to counteract entity expansion you have to + disable the feature:: + + REXML::Document.entity_expansion_limit = 0 + + libxml-ruby and hpricot don't expand entities in their default configuration. + + + PHP + --- + + PHP's SimpleXML API is vulnerable to quadratic entity expansion and loads + entities from local and remote resources. The option ``LIBXML_NONET`` disables + network access but still allows local file access. ``LIBXML_NOENT`` seems to + have no effect on entity expansion in PHP 5.4.6. + + + C# / .NET / Mono + ---------------- + + Information in `XML DoS and Defenses (MSDN)`_ suggest that .NET is + vulnerable with its default settings. The article contains code snippets + how to create a secure XML reader:: + + XmlReaderSettings settings = new XmlReaderSettings(); + settings.ProhibitDtd = false; + settings.MaxCharactersFromEntities = 1024; + settings.XmlResolver = null; + XmlReader reader = XmlReader.Create(stream, settings); + + + Java + ---- + + Untested. The documentation of Xerces and its `Xerces SecurityMananger`_ + sounds like Xerces is also vulnerable to billion laugh attacks with its + default settings. It also does entity resolving when an + ``org.xml.sax.EntityResolver`` is configured. I'm not yet sure about the + default setting here. + + Java specialists suggest to have a custom builder factory:: + + DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance(); + builderFactory.setXIncludeAware(False); + builderFactory.setExpandEntityReferences(False); + builderFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, True); + # either + builderFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", True); + # or if you need DTDs + builderFactory.setFeature("http://xml.org/sax/features/external-general-entities", False); + builderFactory.setFeature("http://xml.org/sax/features/external-parameter-entities", False); + builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", False); + builderFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-dtd-grammar", False); + + + TODO + ==== + + * DOM: Use xml.dom.xmlbuilder options for entity handling + * SAX: take feature_external_ges and feature_external_pes (?) into account + * test experimental monkey patching of stdlib modules + * improve documentation + + + License + ======= + + Copyright (c) 2013-2017 by Christian Heimes + + Licensed to PSF under a Contributor Agreement. + + See https://www.python.org/psf/license for licensing details. + + + Acknowledgements + ================ + + Brett Cannon (Python Core developer) + review and code cleanup + + Antoine Pitrou (Python Core developer) + code review + + Aaron Patterson, Ben Murphy and Michael Koziarski (Ruby community) + Many thanks to Aaron, Ben and Michael from the Ruby community for their + report and assistance. + + Thierry Carrez (OpenStack) + Many thanks to Thierry for his report to the Python Security Response + Team on behalf of the OpenStack security team. + + Carl Meyer (Django) + Many thanks to Carl for his report to PSRT on behalf of the Django security + team. + + Daniel Veillard (libxml2) + Many thanks to Daniel for his insight and assistance with libxml2. + + semantics GmbH (https://www.semantics.de/) + Many thanks to my employer semantics for letting me work on the issue + during working hours as part of semantics's open source initiative. + + + References + ========== + + * `XML DoS and Defenses (MSDN)`_ + * `Billion Laughs`_ on Wikipedia + * `ZIP bomb`_ on Wikipedia + * `Configure SAX parsers for secure processing`_ + * `Testing for XML Injection`_ + + .. _defusedxml package: https://github.com/tiran/defusedxml + .. _defusedxml on PyPI: https://pypi.python.org/pypi/defusedxml + .. _defusedexpat package: https://github.com/tiran/defusedexpat + .. _defusedexpat on PyPI: https://pypi.python.org/pypi/defusedexpat + .. _modified expat: https://github.com/tiran/expat + .. _expat parser: http://expat.sourceforge.net/ + .. _Attacking XML Security: https://www.isecpartners.com/media/12976/iSEC-HILL-Attacking-XML-Security-bh07.pdf + .. _Billion Laughs: https://en.wikipedia.org/wiki/Billion_laughs + .. _XML DoS and Defenses (MSDN): https://msdn.microsoft.com/en-us/magazine/ee335713.aspx + .. _ZIP bomb: https://en.wikipedia.org/wiki/Zip_bomb + .. _DTD: https://en.wikipedia.org/wiki/Document_Type_Definition + .. _PI: https://en.wikipedia.org/wiki/Processing_Instruction + .. _Avoid the dangers of XPath injection: http://www.ibm.com/developerworks/xml/library/x-xpathinjection/index.html + .. _Configure SAX parsers for secure processing: http://www.ibm.com/developerworks/xml/library/x-tipcfsx/index.html + .. _Testing for XML Injection: https://www.owasp.org/index.php/Testing_for_XML_Injection_(OWASP-DV-008) + .. _Xerces SecurityMananger: https://xerces.apache.org/xerces2-j/javadocs/xerces2/org/apache/xerces/util/SecurityManager.html + .. _XML Inclusion: https://www.w3.org/TR/xinclude/#include_element + + Changelog + ========= + + defusedxml 0.7.1 + --------------------- + + *Release date: 08-Mar-2021* + + - Fix regression ``defusedxml.ElementTree.ParseError`` (#63) + The ``ParseError`` exception is now the same class object as + ``xml.etree.ElementTree.ParseError`` again. + + + defusedxml 0.7.0 + ---------------- + + *Release date: 4-Mar-2021* + + - No changes + + + defusedxml 0.7.0rc2 + ------------------- + + *Release date: 12-Jan-2021* + + - Re-add and deprecate ``defusedxml.cElementTree`` + - Use GitHub Actions instead of TravisCI + - Restore ``ElementTree`` attribute of ``xml.etree`` module after patching + + defusedxml 0.7.0rc1 + ------------------- + + *Release date: 04-May-2020* + + - Add support for Python 3.9 + - ``defusedxml.cElementTree`` is not available with Python 3.9. + - Python 2 is deprecate. Support for Python 2 will be removed in 0.8.0. + + + defusedxml 0.6.0 + ---------------- + + *Release date: 17-Apr-2019* + + - Increase test coverage. + - Add badges to README. + + + defusedxml 0.6.0rc1 + ------------------- + + *Release date: 14-Apr-2019* + + - Test on Python 3.7 stable and 3.8-dev + - Drop support for Python 3.4 + - No longer pass *html* argument to XMLParse. It has been deprecated and + ignored for a long time. The DefusedXMLParser still takes a html argument. + A deprecation warning is issued when the argument is False and a TypeError + when it's True. + - defusedxml now fails early when pyexpat stdlib module is not available or + broken. + - defusedxml.ElementTree.__all__ now lists ParseError as public attribute. + - The defusedxml.ElementTree and defusedxml.cElementTree modules had a typo + and used XMLParse instead of XMLParser as an alias for DefusedXMLParser. + Both the old and fixed name are now available. + + + defusedxml 0.5.0 + ---------------- + + *Release date: 07-Feb-2017* + + - No changes + + + defusedxml 0.5.0.rc1 + -------------------- + + *Release date: 28-Jan-2017* + + - Add compatibility with Python 3.6 + - Drop support for Python 2.6, 3.1, 3.2, 3.3 + - Fix lxml tests (XMLSyntaxError: Detected an entity reference loop) + + + defusedxml 0.4.1 + ---------------- + + *Release date: 28-Mar-2013* + + - Add more demo exploits, e.g. python_external.py and Xalan XSLT demos. + - Improved documentation. + + + defusedxml 0.4 + -------------- + + *Release date: 25-Feb-2013* + + - As per http://seclists.org/oss-sec/2013/q1/340 please REJECT + CVE-2013-0278, CVE-2013-0279 and CVE-2013-0280 and use CVE-2013-1664, + CVE-2013-1665 for OpenStack/etc. + - Add missing parser_list argument to sax.make_parser(). The argument is + ignored, though. (thanks to Florian Apolloner) + - Add demo exploit for external entity attack on Python's SAX parser, XML-RPC + and WebDAV. + + + defusedxml 0.3 + -------------- + + *Release date: 19-Feb-2013* + + - Improve documentation + + + defusedxml 0.2 + -------------- + + *Release date: 15-Feb-2013* + + - Rename ExternalEntitiesForbidden to ExternalReferenceForbidden + - Rename defusedxml.lxml.check_dtd() to check_docinfo() + - Unify argument names in callbacks + - Add arguments and formatted representation to exceptions + - Add forbid_external argument to all functions and classes + - More tests + - LOTS of documentation + - Add example code for other languages (Ruby, Perl, PHP) and parsers (Genshi) + - Add protection against XML and gzip attacks to xmlrpclib + + defusedxml 0.1 + -------------- + + *Release date: 08-Feb-2013* + + - Initial and internal release for PSRT review + +Keywords: xml bomb DoS +Platform: all +Classifier: Development Status :: 5 - Production/Stable +Classifier: Intended Audience :: Developers +Classifier: License :: OSI Approved :: Python Software Foundation License +Classifier: Natural Language :: English +Classifier: Programming Language :: Python +Classifier: Programming Language :: Python :: 2 +Classifier: Programming Language :: Python :: 2.7 +Classifier: Programming Language :: Python :: 3 +Classifier: Programming Language :: Python :: 3.5 +Classifier: Programming Language :: Python :: 3.6 +Classifier: Programming Language :: Python :: 3.7 +Classifier: Programming Language :: Python :: 3.8 +Classifier: Programming Language :: Python :: 3.9 +Classifier: Topic :: Text Processing :: Markup :: XML +Requires-Python: >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.* diff -Nru defusedxml-0.7.1/defusedxml.egg-info/SOURCES.txt defusedxml-0.7.1/defusedxml.egg-info/SOURCES.txt --- defusedxml-0.7.1/defusedxml.egg-info/SOURCES.txt 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/defusedxml.egg-info/SOURCES.txt 2021-03-08 10:59:07.000000000 +0000 @@ -0,0 +1,54 @@ +.coveragerc +.gitignore +.hgignore +CHANGES.txt +LICENSE +MANIFEST.in +Makefile +README.html +README.md +README.txt +SECURITY.md +pyproject.toml +setup.cfg +setup.py +tests.py +tox.ini +void.css +.github/workflows/main.yml +defusedxml/ElementTree.py +defusedxml/__init__.py +defusedxml/cElementTree.py +defusedxml/common.py +defusedxml/expatbuilder.py +defusedxml/expatreader.py +defusedxml/lxml.py +defusedxml/minidom.py +defusedxml/pulldom.py +defusedxml/sax.py +defusedxml/xmlrpc.py +defusedxml.egg-info/PKG-INFO +defusedxml.egg-info/SOURCES.txt +defusedxml.egg-info/dependency_links.txt +defusedxml.egg-info/top_level.txt +other/README.txt +other/exploit_webdav.py +other/exploit_xmlrpc.py +other/perl.pl +other/php.php +other/python_external.py +other/python_genshi.py +other/ruby-hpricot.rb +other/ruby-libxml.rb +other/ruby-rexml.rb +xmltestdata/cyclic.xml +xmltestdata/dtd.xml +xmltestdata/external.xml +xmltestdata/external_file.xml +xmltestdata/quadratic.xml +xmltestdata/simple-ns.xml +xmltestdata/simple.xml +xmltestdata/xalan_exec.xsl +xmltestdata/xalan_write.xsl +xmltestdata/xmlbomb.xml +xmltestdata/xmlbomb2.xml \ No newline at end of file diff -Nru defusedxml-0.7.1/defusedxml.egg-info/dependency_links.txt defusedxml-0.7.1/defusedxml.egg-info/dependency_links.txt --- defusedxml-0.7.1/defusedxml.egg-info/dependency_links.txt 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/defusedxml.egg-info/dependency_links.txt 2021-03-08 10:59:07.000000000 +0000 @@ -0,0 +1 @@ + diff -Nru defusedxml-0.7.1/defusedxml.egg-info/top_level.txt defusedxml-0.7.1/defusedxml.egg-info/top_level.txt --- defusedxml-0.7.1/defusedxml.egg-info/top_level.txt 1970-01-01 00:00:00.000000000 +0000 +++ defusedxml-0.7.1/defusedxml.egg-info/top_level.txt 2021-03-08 10:59:07.000000000 +0000 @@ -0,0 +1 @@ +defusedxml diff -Nru defusedxml-0.7.1/setup.cfg defusedxml-0.7.1/setup.cfg --- defusedxml-0.7.1/setup.cfg 2021-03-08 10:58:00.000000000 +0000 +++ defusedxml-0.7.1/setup.cfg 2021-03-08 10:59:07.593425000 +0000 @@ -4,3 +4,8 @@ [aliases] packages = clean --all egg_info bdist_wheel sdist --format=gztar release = packages register upload + +[egg_info] +tag_build = +tag_date = 0 +