[原文]Cisco Secure Access Control Server for Windows (ACS Windows) and Cisco Secure Access Control Server Solution Engine (ACS Solution Engine) 3.3.1, when the EAP-TLS protocol is enabled, does not properly handle expired or untrusted certificates, which allows remote attackers to bypass authentication and gain unauthorized access via a "cryptographically correct" certificate with valid fields such as the username.
Cisco Secure Access Control Server EAP-TLS Authentication Bypass
Remote / Network Access
Loss of Confidentiality
Secure Access Control Server for Windows and Secure Access Control Server Solution Engine, when they are configured to use Extensible Authentication Protocol-Transport Layer Security (EAP-TLS), contain a flaw that may allow an attacker to bypass security authentication. The issue is triggered when the attacker authenticates using a cryptographically correct certificate containing a valid username. It is possible that the flaw may allow the attacker access to the entire network resulting in a loss of confidentiality. Note: this vulnerability is not exploitable if EAP-TLS is configured with binary comparison of user certificates as the only comparison method and if the user entry in Lightweight Directory Access Protocol/Active Directory (LDAP/AD) contains only valid certificates.
Upgrade to version 3.3.2 or higher, as it has been reported to fix this vulnerability. Additionally, Cisco Systems, Inc. has released patches to address this vulnerability.