CVE-2010-3316 in Linux-PAM
Summary
by MITRE
The run_coprocess function in pam_xauth.c in the pam_xauth module in Linux-PAM (aka pam) before 1.1.2 does not check the return values of the setuid, setgid, and setgroups system calls, which might allow local users to read arbitrary files by executing a program that relies on the pam_xauth PAM check.
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Analysis
by VulDB Data Team • 10/13/2021
The vulnerability described in CVE-2010-3316 resides within the pam_xauth module of Linux-PAM, specifically in the run_coprocess function located in pam_xauth.c. This flaw represents a critical security oversight that affects Linux-PAM versions prior to 1.1.2, creating a potential privilege escalation vector for local attackers. The vulnerability stems from inadequate error handling within the authentication module's code execution flow, where the function fails to validate the success or failure of critical system calls that alter process privileges.
The technical implementation of this vulnerability exploits the absence of return value validation for three essential system calls: setuid, setgid, and setgroups. These system calls are fundamental to Unix-like operating systems for managing process ownership and group memberships. When the run_coprocess function executes without verifying the outcomes of these privilege modification operations, it creates a scenario where subsequent code execution may proceed with compromised or unexpected privilege levels. This failure in validation creates a condition where local users can manipulate the execution environment to gain unauthorized access to resources that should otherwise be protected.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to craft specific programs that leverage the flawed pam_xauth module to read arbitrary files. This capability represents a significant breach in the security model of the authentication framework, as it allows local users to bypass normal access controls and potentially access sensitive information that would typically require elevated privileges or direct file system access. The vulnerability essentially provides a pathway for privilege elevation that operates through the authentication subsystem rather than traditional exploitation vectors.
The security implications of this flaw align with CWE-252, which addresses the issue of unchecked return values in security-critical functions. This vulnerability also maps to ATT&CK technique T1068, which describes the exploitation of local privilege escalation mechanisms. The attack vector specifically targets the authentication process through the PAM framework, where attackers can manipulate program execution to achieve unauthorized file access. This represents a sophisticated attack pattern that leverages the trust placed in the authentication subsystem to bypass security controls.
Mitigation strategies for this vulnerability require immediate patching of affected Linux-PAM installations to version 1.1.2 or later, which contains the necessary fixes for proper return value validation. Additionally, system administrators should implement monitoring for unauthorized privilege changes and conduct thorough security audits of PAM module configurations. The remediation process should include verification that all system calls are properly validated and that appropriate error handling mechanisms are in place to prevent similar issues in other authentication modules. Organizations should also consider implementing principle of least privilege configurations and regular security assessments to identify potential similar vulnerabilities in other security-critical components of their authentication infrastructure.