CVE-2003-0388 in Linux
Summary
by MITRE
pam_wheel in Linux-PAM 0.78, with the trust option enabled and the use_uid option disabled, allows local users to spoof log entries and gain privileges by causing getlogin() to return a spoofed user name.
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Analysis
by VulDB Data Team • 11/09/2024
The vulnerability identified as CVE-2003-0388 represents a critical security flaw in the Linux Pluggable Authentication Modules framework, specifically within the pam_wheel module version 0.78. This issue arises from improper handling of user authentication contexts when specific configuration options are enabled, creating a pathway for local privilege escalation and audit bypass. The vulnerability is particularly concerning because it directly impacts the integrity of system logging and authentication mechanisms that are fundamental to security monitoring and access control.
The technical root cause of this vulnerability stems from the pam_wheel module's behavior when processing authentication requests under specific conditions. When the trust option is enabled alongside the use_uid option being disabled, the module fails to properly validate the authenticity of user identification information. The flaw occurs because getlogin() system call, which is responsible for retrieving the login name of the current user, can be manipulated by local attackers to return a spoofed username. This spoofing capability directly undermines the module's ability to accurately verify user identity, allowing malicious users to bypass authentication checks that should restrict access to privileged operations.
The operational impact of this vulnerability extends beyond simple privilege escalation to include significant audit trail corruption and security monitoring bypass. Attackers can exploit this flaw to gain unauthorized access to system resources that should be restricted to specific user groups, typically those with wheel group membership or administrative privileges. The spoofing capability enables malicious users to create false log entries that appear to originate from legitimate privileged accounts, making it extremely difficult for system administrators to detect unauthorized access attempts through traditional monitoring mechanisms. This vulnerability essentially undermines the trust model that authentication systems rely upon for maintaining security boundaries.
The vulnerability manifests through a specific configuration interaction that requires both the trust option and the disabling of use_uid in the pam_wheel module configuration. This configuration creates a dangerous state where the module becomes vulnerable to user spoofing attacks, as the system cannot properly distinguish between legitimate and forged authentication requests. The attack vector is particularly insidious because it operates at the authentication layer, meaning that successful exploitation can lead to complete system compromise without requiring additional attack vectors. This type of vulnerability is classified under CWE-284 Access Control and aligns with ATT&CK technique T1068, which covers Local Privilege Escalation through authentication bypass mechanisms.
Mitigation strategies for CVE-2003-0388 focus on proper configuration management and system hardening practices. The primary recommendation is to either disable the trust option in pam_wheel configuration or ensure that use_uid is properly enabled to prevent spoofing attacks. System administrators should implement strict configuration auditing to verify that authentication modules are properly configured according to security best practices. Additionally, implementing proper monitoring and alerting mechanisms can help detect anomalous authentication patterns that might indicate exploitation attempts. Regular security updates and patches should be applied to ensure that the system is running a version of Linux-PAM that does not contain this vulnerability. The remediation process also includes reviewing and strengthening overall system logging practices to maintain audit integrity even when individual authentication modules are compromised.