David Ward created XALANJ-2557:
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Summary: Security: Every namespace declared by the stylesheet is
registered as an extension namespace, making it virtually impossible to scan
for 'dangerous' namespaces in a stylesheet
Key: XALANJ-2557
URL: https://issues.apache.org/jira/browse/XALANJ-2557
Project: XalanJ2
Issue Type: Bug
Security Level: No security risk; visible to anyone (Ordinary problems in
Xalan projects. Anybody can view the issue.)
Components: Xalan-extensions
Affects Versions: 2.7.1
Reporter: David Ward
Assignee: Steven J. Hathaway
Priority: Critical
As per the documentation:
http://xml.apache.org/xalan-j/extensions.html#java-namespace-declare
Although the namespace declarations for the class and package formats are
shown with the xalan:// prefix, the current implementation for those formats
will simply use the string to the right of the rightmost forward slash as
the
Java class name. This format, however, is the preferred format for extension
namespace declarations.
It's not crystal clear in the above documentation that any class URI can be
used. Not just those with a certain prefix. For example
http://foo/java.io.File
will be registered with the
org.apache.xalan.extensions.ExtensionHandlerJavaClass because the suggested
class URI format is not enforced.
This is a quandary for those of us that need to use the Java extension space,
but want to use an XML filter to provide a modicum security in order to limit
what extensions can be used. FEATURE_SECURE_PROCESSING seems to be all or
nothing. Given the above, the use of a Java extension is difficult to detect.
Perhaps there is room to add a feature to enforce the suggested class URI
format in order to provide a better middle of the road approach to security.
An example 'innocent' looking stylesheet
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:file="http://myfoo/java.io.File"; version="1.0"
extension-element-prefixes="file">
<xsl:template match="/">
<xsl:variable name="f" select="file:new("/tmp/iwashere")"/>
<xsl:variable name="c" select="file:createNewFile($f)"/>
</xsl:template>
</xsl:stylesheet>
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