CVE-2012-5536 in Linux
Summary
by MITRE
A certain Red Hat build of the pam_ssh_agent_auth module on Red Hat Enterprise Linux (RHEL) 6 and Fedora Rawhide calls the glibc error function instead of the error function in the OpenSSH codebase, which allows local users to obtain sensitive information from process memory or possibly gain privileges via crafted use of an application that relies on this module, as demonstrated by su and sudo.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2012-5536 affects the pam_ssh_agent_auth module in Red Hat Enterprise Linux 6 and Fedora Rawhide systems, representing a critical security flaw in the authentication framework that could enable local privilege escalation and information disclosure. This issue stems from a fundamental mismatch in error handling implementation between the glibc library and the OpenSSH codebase, creating a vector for exploitation that leverages the module's improper memory management practices. The flaw specifically manifests when applications relying on this PAM module execute with elevated privileges, making it particularly dangerous in environments where privilege escalation is a primary concern.
The technical root cause of this vulnerability lies in the improper error handling mechanism within the pam_ssh_agent_auth module, where the code incorrectly invokes the glibc error function rather than the corresponding OpenSSH error function. This discrepancy creates a memory access pattern that allows local attackers to potentially read sensitive data from process memory spaces, including authentication tokens, session information, and other confidential data that should remain protected. The error function call mismatch results in improper memory cleanup and potential information leakage that can be exploited through carefully crafted input to applications that depend on this authentication module. According to CWE-248, this represents an improper exception handling vulnerability where the system fails to properly manage error conditions, leading to unintended information disclosure.
The operational impact of this vulnerability extends beyond simple information disclosure to include potential privilege escalation capabilities that could allow local attackers to gain elevated system privileges. When applications such as su and sudo utilize the affected pam_ssh_agent_auth module, attackers can exploit the memory access patterns to extract authentication credentials or session data that could then be used to escalate their privileges within the system. The vulnerability affects the core authentication infrastructure of affected systems, potentially compromising the integrity of the entire authentication process. This type of vulnerability aligns with ATT&CK technique T1068 which involves privilege escalation through exploitation of system vulnerabilities, and T1005 which covers data from local system storage, making it particularly dangerous for enterprise environments where multiple users may have access to systems running vulnerable software versions.
Mitigation strategies for CVE-2012-5536 require immediate patching of the affected Red Hat Enterprise Linux 6 and Fedora Rawhide systems, as well as implementation of proper monitoring for unauthorized access attempts that might exploit this vulnerability. System administrators should ensure that all instances of the pam_ssh_agent_auth module are updated to versions that properly handle error conditions using the correct OpenSSH error functions rather than glibc implementations. Additionally, implementing proper access controls and privilege separation can help reduce the potential impact of exploitation attempts, while monitoring for unusual memory access patterns or authentication failures can provide early detection of attempted exploitation. Organizations should also consider disabling the affected module if it is not essential for their authentication workflows, and regularly audit their PAM configuration to ensure that only necessary authentication modules are active. The vulnerability demonstrates the importance of maintaining proper function call consistency in security-critical code and the potential consequences of improper error handling in authentication modules that can affect the entire system security posture.