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AUSCERT External Security Bulletin Redistribution
ESB-2009.1199
Shibboleth Service Provider Security Advisory [17 August 2009]
19 August 2009
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AusCERT Security Bulletin Summary
---------------------------------
Product: Shibboleth 2.2
Shibboleth 1.3.2 and prior
Publisher: Shibboleth
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Provide Misleading Information -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2009-2417
Reference: ESB-2009.1186
Original Bulletin:
http://shibboleth.internet2.edu/secadv/secadv_20090817.txt
http://shibboleth.internet2.edu/secadv/secadv_20090817a.txt
Comment: This bulletin contains two (2) Shibboleth security advisories.
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Shibboleth Service Provider Security Advisory [17 August 2009]
Updated versions of the Shibboleth 1.3.x and 2.x Service Provider
software are now available which correct a security issue.
Platforms on which libcurl is an OS-supplied component, such as
Linux or OS X, will also need to ensure their vendor has supplied
an updated curl package to correct a related issue.
Shibboleth SP software improperly handles certificate names
============================================================
It was recently discovered that a number of public certificate
authorities were willing to issue certificates in response to
requests containing null (0) characters embedded in the subject
or subjectAltName fields. This in turn led to the discovery that
most implementations of SSL/TLS name matching were vulnerable to
a variety of attacks, some extremely serious, when such certificates
are used.
e.g., http://www.theregister.co.uk/2009/07/30/universal_ssl_certificate/
Upon investigation, it was discovered that the Service Provider
software is affected by this issue in two ways:
- - via a dependency on libcurl for SSL server name verification
- - while processing signing certificates against trusted "key names"
The first is a vulnerability in libcurl itself, and has been addressed
by its author in version 7.19.6.
http://curl.haxx.se/docs/adv_20090812.html
The second is a similar vulnerablity in the Shibboleth code itself.
In both cases, deployments are affected only when relying on the "PKIX"
style of trust validation included in the Shibboleth software. This is
triggered by the absence of explicit certificate information in the SAML
metadata provided to the SP, and the reliance on certificate authorities
found in the <KeyAuthority> metadata extension element.
Recommendations
- ---------------
Affected sites using 1.3.x should upgrade to the latest patched release,
1.3.3.
Affected sites using 2.x should upgrade to the latest patched release,
2.2.1.
Sites that have deployed by building their own copy of libcurl should
ensure that they upgrade to 7.19.6 of that package, or patch older
versions as desired.
Sites that rely on an OS-supplied version of libcurl will need to
contact their OS vendor for a fixed version, or manually build a
new or patched version.
Credits
- -------
Thanks to Ian Young for highlighting this issue, and to Daniel Stenberg
for addressing the vulnerability in libcurl.
URL for this Security Advisory:
http://shibboleth.internet2.edu/secadv/secadv_20090817.txt
Shibboleth Service Provider Security Advisory [17 August 2009]
An updated version of the Shibboleth 2.x Service Provider
software is now available which corrects a security issue.
Shibboleth SP software improperly evaluates KeyDescriptors
============================================================
The Shibboleth software supports the use of SAML metadata to
identify authentication and encryption keys by means of the
<KeyDescriptor> element. In previous versions, the software
was improperly ignoring the "use" attribute and treating all
elements as valid for both signing/TLS and encryption.
In many cases this is a valid assumption, but if specific
keypairs were meant to be used for only one of those purposes,
weaknesses in the intended security of the deployment could
arise.
Deployments are affected only when interacting with SAML 2.0-
capable Identity Providers and when their metadata identifies
keys for signing or encryption only, by means of the "use"
attribute.
This vulnerability does NOT extend to accepting keys that are
not present in the metadata.
Recommendations
- ---------------
Sites using 1.3.x are NOT affected by this issue.
Affected sites using 2.x should upgrade to the latest patched release,
2.2.1.
The vulnerability is actually found in the supporting libraries,
and if necessary can be corrected by upgrading only the xmltooling
and opensaml libraries to versions 1.2.1 and 2.2.1 respectively.
URL for this Security Advisory:
http://shibboleth.internet2.edu/secadv/secadv_20090817a.txt
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Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
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