CVE-2012-5424 in Secure Access Control Server
Summary
by MITRE
Cisco Secure Access Control System (ACS) 5.x before 5.2 Patch 11 and 5.3 before 5.3 Patch 7, when a certain configuration involving TACACS+ and LDAP is used, does not properly validate passwords, which allows remote attackers to bypass authentication by sending a valid username and a crafted password string, aka Bug ID CSCuc65634.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/19/2021
The vulnerability CVE-2012-5424 affects Cisco Secure Access Control System versions 5.x before 5.2 Patch 11 and 5.3 before 5.3 Patch 7, representing a critical authentication bypass flaw that undermines the security posture of network access control systems. This vulnerability specifically manifests when the system employs a particular configuration that combines TACACS+ and LDAP authentication mechanisms, creating a dangerous condition where password validation becomes ineffective. The flaw allows remote attackers to circumvent authentication controls by exploiting a weakness in how the system processes authentication requests, particularly when handling password validation logic.
The technical implementation of this vulnerability stems from improper input validation within the authentication processing pipeline of the Cisco ACS platform. When a valid username is submitted alongside a crafted password string, the system fails to properly validate the password against the configured authentication backend. This weakness creates a scenario where attackers can authenticate successfully without providing valid credentials, effectively bypassing the entire authentication mechanism. The vulnerability operates at the application layer and can be exploited remotely without requiring prior authentication, making it particularly dangerous for network infrastructure security. The issue has been classified under CWE-287, which addresses improper authentication, and aligns with ATT&CK technique T1078 for valid accounts and T1566 for credential access through authentication bypass methods.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to gain elevated privileges within the network infrastructure controlled by the affected Cisco ACS system. Network administrators who rely on this system for controlling access to network resources face significant risk, as successful exploitation could allow attackers to gain administrative access to network devices, servers, and applications protected by the ACS infrastructure. The vulnerability affects the integrity and confidentiality of the authentication system, potentially enabling attackers to establish persistent access points within the network environment. Organizations using this authentication system may experience unauthorized network penetration, data exfiltration, and privilege escalation attacks that could compromise the entire network access control framework.
Organizations should immediately implement mitigations including applying the relevant security patches released by Cisco, specifically versions 5.2 Patch 11 and 5.3 Patch 7, which address the password validation flaw. Network segmentation and monitoring should be enhanced to detect unusual authentication patterns that might indicate exploitation attempts. Additionally, organizations should review their TACACS+ and LDAP configuration to ensure proper authentication validation is enforced and consider implementing additional authentication layers such as multi-factor authentication to reduce the impact of potential exploitation. The vulnerability demonstrates the critical importance of proper input validation in authentication systems and serves as a reminder of the necessity for regular security updates and configuration reviews in enterprise network infrastructure.