Shibboleth konsortiet skickade ut nedanstående Security Advisory den 16 december 2022. Alla som använder Shibboleth Identity Provider eller OpenSAML-Java rekommenderas starkt att följa konsortiet rekommendationer snarast.
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Shibboleth Identity Provider Security Advisory [12 December 2022]
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OpenSAML-Java Security Advisory [12 December 2022]
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Older releases of the Shibboleth Identity Provider and OpenSAML-Java
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library are potentially vulnerable to attacks ranging from denial of
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service to remote code execution when given specially-crafted
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encrypted XML to decrypt. Some decryption use cases include
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unauthenticated message processing, so are widely accessible.
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While the current releases of both software products (V4.2.0+) are
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believed to be protected from the worst implications of this issue,
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many people operate older releases of both the Identity Provider and
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OpenSAML, so we are publishing this advisory in part as a courtesy.
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It is believed that the worst outcomes on older versions also depend
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on the use of non-current releases of the Java JDK, even as recent
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as those prior to
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July of 2022.
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At this time, it is believed that the risk of similar attacks in the
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Shibboleth SP are not significant. We will update this, and publish a
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second advisory in the event this determination changes.
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OpenSAML and IdP mis-handle malicious encrypted XML content
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======================================================================
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The XML Encryption specification, much as the original XML Signature
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specification, contains an over-abundance of generality in various
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areas, including the potential use of XSLT and XPath "transforms"
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as processing instructions while calculating the encrypted content
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to decrypt.
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SAML provides very specific guidelines for how signed XML needs to
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look, allowing pre-validation to prevent many problems. It provides
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much less guidance on this matter for encrypted XML.
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The OpenSAML Java library, up to and including V4.2.0, does not
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perform sufficient validation on the content to outright prevent
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execution of some malicious transforms. (OpenSAML V4.2.0 is present
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in the V4.2.x releases of the Shibboleth Identity Provider.)
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However, the Santuario XML Signature/Encryption library release (2.3.0)
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used by these versions of our software contains a default-on secure
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processing mode that precludes the worst of these attacks out of the
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box, and so we know of no immediately practical attacks against these
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versions of our software.
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Unfortunately, older versions of our software rely on older Santuario
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versions that do not default to this secure processing mode. They are
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therefore potentially vulnerable, and these attacks are able to exploit
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critical security vulnerabilities in versions of Java whose XSLT
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implementation has not been patched.
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There have been at least two remote code execution vulnerabilities
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reported against Xalan-J, and in turn against Java, in the past 8 years,
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one as recent as this past summer. As a result. versions of Java with
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patch levels older than August 2022 are believed to be vulnerable to
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at least one such issue.
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Note that the actual Java LTS release (Java 8, Java 11, Java 17) is
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not the relevant issue, but the underlying patch level of a given Java
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version. All of the sources of OpenJDK provide routine patch updates
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on a quarterly basis and these updates are critical. It is also crucial
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to use these LTS releases rather than "feature releases" such as
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Java 12-16, etc. due to the risk of missing out on such fixes
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. We will include an enhancement in all future releases of OpenSAML to harden the library against this class of attacks to the greatest extent possible. Recommendations ===============
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Review the versions of Java and the Identity Provider and OpenSAML
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software in your deployment. Make sure that Java is fully patched
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and current for whichever LTS release you are using, and take steps
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to ensure this remains true.
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Note that the Shibboleth Project does not distribute Java in any of
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our packaging, most particularly on Windows, where there is no
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built-in source of Java and maintaining currency requires additional
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effort. Some third-party packaging sources do include Java and you
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should ensure you are staying up to date via those sources.
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This Red Hat bug report [1] on one of the vulnerabilities mentions
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the specific patch levels released this summer that address the
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latest issue. Those Oracle patch levels refer to Java "in general"
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and may not apply in specific instances where vendors have distributed
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Java themselves (e.g., Debian and so on). When in doubt, always use
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"the latest" Java for your LTS version and platform.
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Obviously you should be taking steps to upgrade to a current IdP
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version, but the advice above is critical if you cannot do so quickly.
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While we do believe the older versions of our software are likely safe
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from the worst of the vulnerabilities provided Java is current, we do
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not believe that the risk of future attacks is insignificant, and so
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this is not a recommended long term answer.
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In the event that upgrading promptly is impossible (which would imply
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you should be considering alternatives),
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a reasonable precaution is to update your older deployment to xmlsec-2.3.0.jar by following these steps: 1. Stop servlet container. 2. Remove the existing version of xmlsec-X.X.X.jar from dist/webapp/WEB-INF/lib
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While we believe this is a compatible change for all V4.x IdP
releases, we have not yet tested this workaround, but will update
this advisory if and when we have. We do not know whether this is
likely to help on releases prior to V4.0.0 and have no plans to
investigate this.
We will include an enhancement in all future releases of OpenSAML
to harden the library against this class of attacks to the greatest
extent possible.
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3. Download, verify, and copy in the newer version from [2] to that same location (or if you prefer, to edit-webapp/WEB-INF/lib). 4. Rebuild the war via the usual build.sh/build.bat command. 5. Start servlet container. This is a compatible change for all V4.x IdP releases. We do not know whether this is compatible with older versions. Credits =======
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Khoadha of Viettel Cyber Security
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[1] https://bugzilla.redhat.com/show_bug.cgi?id=2108554
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[2] https://repo1.maven.org/maven2/org/apache/santuario/xmlsec/2.3.0/
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URL for this Security Advisory:
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https://shibboleth.net/community/advisories/secadv_20221216.txt
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