Update php-saml library to 2.10.5

How it was found

The php-saml library as used by our SSO implementation had a minor security patch in 2.10.4 as per https://github.com/onelogin/php-saml/commit/949359f5cad5e1d085c4e5447d9aa8f49a6e82a1. So we should update this in our next minor releases.

Security update for signature validation on LogoutRequest/LogoutResponse.

In order to verify Signatures on Logoutrequests and LogoutResponses we use the verifySignature of the class XMLSecurityKey from the xmlseclibs library. That method end up calling openssl_verify() depending on the signature algorithm used.

The openssl_verify() function returns 1 when the signature was successfully verified, 0 if it failed to verify with the given key, and -1 in case an error occurs. PHP allows translating numerical values to boolean implicitly, with the following correspondences:

• 0 equals false.
• Non-zero equals true.

This means that an implicit conversion to boolean of the values returned by openssl_verify() will convert an error state, signaled by the value -1, to a successful verification of the signature (represented by the boolean true).

The LogoutRequest/LogoutResponse signature validator was performing an implicit conversion > to boolean of the values returned by the verify() method, which subsequently will return the same output as openssl_verify() under most circumstances. This means an error during signature verification is treated as a successful verification by the method.

Since the signature validation of SAMLResponses were not affected, the impact of this security vulnerability is lower, but an update of the php-saml toolkit is recommended.