connector/saml: fix validation bug with multiple Assertion elements #893
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added 2 commits
April 4, 2017 11:11
When a SAML response provided multiple Assertion elements, only the
first one is checked for a valid signature. If the Assertion is
verified, the original Assertion is removed and the canonicalized
version is prepended to the Response. However, if there were
multiple assertions, the second assertion could end up first in the
list of Assertions, even if it was unsigned.
For example this:
<Response>
<!--
Response unsigned. According to SAML spec must check
assertion signature.
-->
<Assertion>
<Signature>
<!-- Correrctly signed assertion -->
</Signature>
</Assertion>
<Assertion>
<!-- Unsigned assertion inserted by attacker-->
</Assertion>
</Response>
could be verified then re-ordered to the following:
<Response>
<!--
Response unsigned. According to SAML spec must check
assertion signature.
-->
<Assertion>
<!-- Unsigned assertion inserted by attacker-->
</Assertion>
<Assertion>
<!-- Canonicalized, correrctly signed assertion -->
</Assertion>
</Response>
Fix this by removing all unverified child elements of the Response,
not just the original assertion.
Introduces SAML tests which execute full response processing and compare user attributes. tesdata now includes a full, self-signed CA and documents signed using xmlsec1. Adds deprication notices to existing tests, but don't remove them since they still provide coverage.
rithujohn191
approved these changes
Apr 4, 2017
mmrath
pushed a commit
to mmrath/dex
that referenced
this pull request
Sep 2, 2019
connector/saml: fix validation bug with multiple Assertion elements
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This diff is so big because the fix reworks the response signature validation. To ensure the refactors work, a new test framework using xmlsec1 was added, which includes a malicious test case that would previously have been accepted.