rspec/rules/S6376/java/rule.adoc

== Why is this an issue?

include::../description.adoc[]

=== Noncompliant code example

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] and https://docs.oracle.com/javase/9/docs/api/javax/xml/validation/SchemaFactory.html[Schema] and https://docs.oracle.com/javase/9/docs/api/javax/xml/transform/TransformerFactory.html[Transformer] JAPX factories:

[source,java]
----
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false); // Noncompliant

SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false); // Noncompliant

SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false); // Noncompliant

TransformerFactory factory = javax.xml.transform.TransformerFactory.newInstance(); 
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false); // Noncompliant
----

For https://dom4j.github.io/[Dom4j] library:

[source,java]
----
SAXReader xmlReader = new SAXReader();
xmlReader.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false); // Noncompliant

----

For http://www.jdom.org/[Jdom2] library:

[source,java]
----
SAXBuilder builder = new SAXBuilder(); 
builder.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, false);  // Noncompliant
----

=== Compliant solution
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] and https://docs.oracle.com/javase/9/docs/api/javax/xml/validation/SchemaFactory.html[Schema] and https://docs.oracle.com/javase/9/docs/api/javax/xml/transform/TransformerFactory.html[Transformer] JAPX factories:

[source,java]
----
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 

SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 

SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 

TransformerFactory factory = javax.xml.transform.TransformerFactory.newInstance(); 
factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 
----

For https://dom4j.github.io/[Dom4j] library:

[source,java]
----
SAXReader xmlReader = new SAXReader();
xmlReader.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); 

----

For http://www.jdom.org/[Jdom2] library:

[source,java]
----
SAXBuilder builder = new SAXBuilder(); 
builder.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);  
----

== Resources

* 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
* https://owasp.org/www-project-top-ten/2017/A4_2017-XML_External_Entities_(XXE)[OWASP Top 10 2017 Category A4] - XML External Entities (XXE)
* https://cheatsheetseries.owasp.org/cheatsheets/XML_External_Entity_Prevention_Cheat_Sheet.html#java[OWASP XXE Prevention Cheat Sheet]
* https://cwe.mitre.org/data/definitions/776[MITRE, CWE-776] - Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Enable XML parsing limitations to prevent Denial of Service attacks.



'''
== Comments And Links
(visible only on this page)

=== on 25 Jan 2022, 10:34:00 Quentin Jaquier wrote:
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.

endif::env-github,rspecator-view[]