16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
131 lines
4.6 KiB
Plaintext
131 lines
4.6 KiB
Plaintext
== Why is this an issue?
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include::../description.adoc[]
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=== Noncompliant code example
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For https://docs.oracle.com/javase/9/docs/api/javax/xml/parsers/DocumentBuilderFactory.html[DocumentBuilder], https://docs.oracle.com/javase/9/docs/api/javax/xml/parsers/SAXParserFactory.html[SAXParser], https://docs.oracle.com/javase/9/docs/api/javax/xml/stream/XMLInputFactory.html[XMLInput], https://docs.oracle.com/javase/9/docs/api/javax/xml/transform/TransformerFactory.html[Transformer] and https://docs.oracle.com/javase/9/docs/api/javax/xml/validation/SchemaFactory.html[Schema] JAPX factories:
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[source,java]
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----
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factory.setXIncludeAware(true); // Noncompliant
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// or
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factory.setFeature("http://apache.org/xml/features/xinclude", true); // Noncompliant
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----
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For https://dom4j.github.io/[Dom4j] library:
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[source,java]
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----
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SAXReader xmlReader = new SAXReader();
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xmlReader.setFeature("http://apache.org/xml/features/xinclude", true); // Noncompliant
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----
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For http://www.jdom.org/[Jdom2] library:
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[source,java]
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----
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SAXBuilder builder = new SAXBuilder();
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builder.setFeature("http://apache.org/xml/features/xinclude", true); // Noncompliant
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----
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=== Compliant solution
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Xinclude is disabled by default and can be explicitely disabled like below.
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For https://docs.oracle.com/javase/9/docs/api/javax/xml/parsers/DocumentBuilderFactory.html[DocumentBuilder], https://docs.oracle.com/javase/9/docs/api/javax/xml/parsers/SAXParserFactory.html[SAXParser], https://docs.oracle.com/javase/9/docs/api/javax/xml/stream/XMLInputFactory.html[XMLInput], https://docs.oracle.com/javase/9/docs/api/javax/xml/transform/TransformerFactory.html[Transformer] and https://docs.oracle.com/javase/9/docs/api/javax/xml/validation/SchemaFactory.html[Schema] JAPX factories:
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[source,java]
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----
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factory.setXIncludeAware(false);
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// or
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factory.setFeature("http://apache.org/xml/features/xinclude", false);
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----
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For https://dom4j.github.io/[Dom4j] library:
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[source,java]
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----
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SAXReader xmlReader = new SAXReader();
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xmlReader.setFeature("http://apache.org/xml/features/xinclude", false);
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----
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For http://www.jdom.org/[Jdom2] library:
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[source,java]
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----
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SAXBuilder builder = new SAXBuilder();
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builder.setFeature("http://apache.org/xml/features/xinclude", false);
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----
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=== Exceptions
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This rule does not raise issues when Xinclude is enabled with a custom ``++EntityResolver++``:
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For DocumentBuilderFactory:
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[source,java]
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----
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DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
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factory.setXIncludeAware(true);
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// ...
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DocumentBuilder builder = factory.newDocumentBuilder();
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builder.setEntityResolver((publicId, systemId) -> new MySafeEntityResolver(publicId, systemId));
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----
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For SAXBuilder:
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[source,java]
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----
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SAXBuilder builder = new SAXBuilder();
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builder.setFeature("http://apache.org/xml/features/xinclude", true);
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builder.setEntityResolver((publicId, systemId) -> new MySafeEntityResolver(publicId, systemId));
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----
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For SAXReader:
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[source,java]
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----
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SAXReader xmlReader = new SAXReader();
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xmlReader.setFeature("http://apache.org/xml/features/xinclude", true);
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xmlReader.setEntityResolver((publicId, systemId) -> new MySafeEntityResolver(publicId, systemId));
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----
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For XMLInputFactory:
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[source,java]
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----
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XMLInputFactory factory = XMLInputFactory.newInstance();
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factory.setProperty("http://apache.org/xml/features/xinclude", true);
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factory.setXMLResolver(new MySafeEntityResolver());
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----
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== Resources
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* https://docs.oracle.com/en/java/javase/13/security/java-api-xml-processing-jaxp-security-guide.html#GUID-8CD65EF5-D113-4D5C-A564-B875C8625FAC[Oracle Java Documentation] - XML External Entity Injection Attack
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* https://owasp.org/www-project-top-ten/2017/A4_2017-XML_External_Entities_(XXE)[OWASP Top 10 2017 Category A4] - XML External Entities (XXE)
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* https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html#java[OWASP XXE Prevention Cheat Sheet]
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* https://cwe.mitre.org/data/definitions/611[MITRE, CWE-611] - Information Exposure Through XML External Entity Reference
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* https://cwe.mitre.org/data/definitions/827[MITRE, CWE-827] - Improper Control of Document Type Definition
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Disable the inclusion of files in XML processing.
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'''
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== Comments And Links
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(visible only on this page)
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=== on 25 Jan 2022, 10:34:00 Quentin Jaquier wrote:
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Quick fixes (for Java): even if it is technically possible to provide a fix that would result in compliant code, it does not sound wise to set properties blindly, as it can have side effects. Fixing the issue requires a careful and good understanding of the overall context of the code.
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endif::env-github,rspecator-view[]
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