CVE-2008-0884 in Red Hat
Summary
by MITRE
The Replace function in the capp-lspp-config script in the (1) lspp-eal4-config-ibm and (2) capp-lspp-eal4-config-hp packages before 0.65-2 in Red Hat Enterprise Linux (RHEL) 5 uses lstat instead of stat to determine the /etc/pam.d/system-auth file permissions, leading to a change to world-writable permissions for the /etc/pam.d/system-auth-ac file, which allows local users to gain privileges by modifying this file.
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Analysis
by VulDB Data Team • 11/15/2017
The vulnerability described in CVE-2008-0884 represents a critical privilege escalation flaw within the Linux Security Performance Profile (LSPP) configuration packages distributed with Red Hat Enterprise Linux 5. This issue stems from a fundamental flaw in the capp-lspp-config script that handles PAM configuration file management during system security profile enforcement. The vulnerability specifically affects the lspp-eal4-config-ibm and capp-lspp-eal4-config-hp packages, which are designed to implement enhanced security configurations for enterprise systems. The flaw manifests when the Replace function attempts to manage permissions for the /etc/pam.d/system-auth-ac file, a critical component in the system's authentication framework that controls access to various security services.
The technical root cause of this vulnerability lies in the improper use of system calls within the configuration script. The script employs lstat instead of stat when determining file permissions for the /etc/pam.d/system-auth file, which creates a significant discrepancy in how file metadata is evaluated. The lstat function retrieves information about a symbolic link itself rather than the file it points to, while stat provides information about the actual file. This distinction becomes critical when the system is processing configuration files that may be symbolic links, leading to incorrect permission assessments and subsequent improper file modifications. According to CWE-255, this represents a weakness in the implementation of permission checks, specifically related to the improper handling of symbolic links in security-sensitive contexts. The vulnerability creates a scenario where the system incorrectly calculates permissions, allowing for the unintended modification of security-critical files.
The operational impact of this vulnerability is severe and directly enables local privilege escalation attacks. When the configuration script executes with elevated privileges during system security profile application, it inadvertently modifies the /etc/pam.d/system-auth-ac file to world-writable permissions. This modification creates a persistent backdoor that allows any local user to modify the authentication configuration, potentially gaining root access or bypassing authentication mechanisms entirely. The vulnerability is particularly dangerous because it operates at the system configuration level, where it can affect the entire authentication framework. Attackers can exploit this by modifying the system-auth-ac file to include malicious authentication modules or alter existing authentication rules, effectively compromising the system's security posture. This vulnerability aligns with ATT&CK technique T1068, which covers the use of local privilege escalation to gain elevated system access. The impact extends beyond simple privilege escalation, as it undermines the fundamental security controls that protect system integrity and authentication services.
The recommended mitigations for this vulnerability involve immediate package updates and careful system administration practices. Organizations should upgrade to version 0.65-2 or later of the affected packages to receive the corrected implementation that properly uses stat instead of lstat for file permission evaluation. Additionally, system administrators should conduct thorough audits of the /etc/pam.d/ directory to ensure that no unauthorized modifications have been made to authentication configuration files. The system should be monitored for any suspicious file permission changes, particularly those that result in world-writable permissions for security-critical files. Implementing proper file integrity monitoring solutions can help detect unauthorized modifications to authentication configuration files. Security teams should also review and validate all system configuration scripts that handle sensitive file permissions to ensure proper use of system calls and avoid similar issues in other security-related components. This vulnerability demonstrates the critical importance of proper file permission handling in security-sensitive contexts and underscores the need for rigorous code review processes in system administration tools. The fix ensures that the configuration script correctly evaluates file permissions through proper use of the stat system call, thereby preventing the unintended modification of authentication configuration files and maintaining system security integrity.