===================================================================== CERT-Renater Note d'Information No. 2009/VULN337 _____________________________________________________________________ DATE : 17/08/2009 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : Shibboleth Service Provider 1.3.x et 2.x ====================================================================== 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 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 ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================