A security advisor was recently issued indicating that if you are using the current Shibboleth SP on your application, it has been identified as vulnerable to forged user attribute data and that UBC’s Shibboleth implementation is impacted.
Shibboleth SP software relies on a generic XML parser to process SAML responses and there are limitations in older versions of the parser that make it impossible to fully disable Document Type Definition (DTD) processing. Through addition/manipulation of a DTD, it is possible to make changes to an XML document that do not break a digital signature but are mishandled by the SP and its libraries. These manipulations can alter the user data passed through to applications behind the SP and result in impersonation attacks and exposure of protected information. While the use of XML Encryption can serve as a mitigation for this bug, it may still be possible to construct attacks in such cases, and the SP does not provide a means to enforce its use.
We have informed all of our CWL Integration Partners about this critical vulnerability and the recommended solution; an updated version of XMLTooling-C (V1.6.3) is available that works around this specific bug.
More information on this vulnerability can be found here:
hxxps://nvd.nist.gov/vuln/detail/CVE-2018-0486 *
hxxps://securitytracker.com/id/1040177
hxxps://lists.debian.org/debian-security-announce/2018/msg00007.html
hxxps://shibboleth.net/community/advisories/secadv_20180112.txt
hxxps://www.debian.org/security/2018/dsa-4085
If you have any questions, please contact us through the webform:
hxxps://web.it.ubc.ca/forms/iam/
*Note: For added security, we have changed links to include an hxxps:// prefix. This removes the hyperlink from the message. Simply copy and paste the URL into a web browser and replace hxxps:// with https://. Together we can keep our information secure.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Shibboleth Service Provider Security Advisory [12 January 2018] An updated version of the Shibboleth Project's XMLTooling library is available which corrects a critical security issue. Shibboleth SP software vulnerable to forged user attribute data ==================================================================== The Service Provider software relies on a generic XML parser to process SAML responses and there are limitations in older versions of the parser that make it impossible to fully disable Document Type Definition (DTD) processing. Through addition/manipulation of a DTD, it's possible to make changes to an XML document that do not break a digital signature but are mishandled by the SP and its libraries. These manipulations can alter the user data passed through to applications behind the SP and result in impersonation attacks and exposure of protected information. While the use of XML Encryption can serve as a mitigation for this bug, it may still be possible to construct attacks in such cases, and the SP does not provide a means to enforce its use. An updated version of XMLTooling-C (V1.6.3) is available that works around this specific bug. While newer versions of the parser are configured by the SP into disallowing the use of a DTD via an environment variable, this feature is not present in the parser used on some supported platforms (notably Red Hat and CentOS 7), so an additional fix is being provided now that an actual DTD exploit has been identified. While it is possible to determine whether one is already immune to this bug, the installation of this patch is a simpler step, and strongly encouraged. Notably, however "current" Windows installs of V2.6.0 and later are *not* impacted by the bug, so this patch can be treated as lower priority on that platform. This vulnerability has been assigned CVE-2018-0486. Recommendations =============== Upgrade to V1.6.3 or later of the XMLTooling-C library and restart the affected processes (shibd, Apache, etc.) Linux installations relying on official RPM packages can upgrade to the latest package versions to obtain the fix. The MacPort has also been updated. Windows systems can upgrade to the latest Service Provider release (V2.6.1.3) which contains the appropriately updated libraries. [1] Credits ======= Philip Huppert, RedTeam Pentesting [1] https://shibboleth.net/downloads/service-provider/2.6.1/ URL for this Security Advisory: https://shibboleth.net/community/advisories/secadv_20180112.txt -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE3KoVAHvtneaQzZUjN4uEVAIneWIFAlpY1OAACgkQN4uEVAIn eWKIhw//RXdMFS0ez8N7+9b9HGoPdWXVPvw+LGK0aVL2tkhHeRiDvzrIJng4o/35 Mm6e02dm4YI2U0aObUH9Ns0AQZLCzUblOaVupysd0NWy0imvieJJHGDuoWLR9DeP ehLH8FOKlGjNHGcmkf70JWpVWPFCdO3J0PXdxrFey2dHbAu5Npf5aQanIvrEtiDu lAvBrEJKasRxZ9zXjrc6Nl7C6Mk+7LOuZLYj2XaQeriRxMWER5ArStdk4VCBxq1G g3RELwdWxwRM3dCg+kQMZTkClvL/uYwJbSrlk6JQus80drJ2u8tPjuRMFkhvBm15 ylEU6d123vISZqRiKoVGsHhz9p3W+EJ5TfWwq8mrxHRLBwyvVVyHePT0aQmGdxiC +uHp4jOiPYh0FLWNqRioo79rOtxpHKQXMqCSoA9v9DtfESkYr/lw4mXcL+ZySY9n 6UXVihz5PLMaqMXWuX590xGIcSpnihMFBOGxymQ8CqNfUhrxZpHsrfh6b78iqIV+ EsOan7w5XJ9GifaOsVy2nT5u5TQ9KQpz9UFAUfNxQ4DiRk6x1sTPnLj0gSy+ttn6 S63QnT6PkIzGdgl+60BXmKiL+4vgYdBetfe3o9ZPFL2zs4nVQxw20zqbyh2ZZZ3Z x9NrMwuDL6IUiK+pdfsVL5EL7UKokmVKRDERit5ElrxzmpT25qA= =fxWs -----END PGP SIGNATURE-----