CVE-2002-1227 in PAM
Summary
by MITRE
PAM 0.76 treats a disabled password as if it were an empty (null) password, which allows local and remote attackers to gain privileges as disabled users.
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Analysis
by VulDB Data Team • 06/30/2024
The vulnerability identified as CVE-2002-1227 represents a critical authentication flaw in the Pluggable Authentication Modules framework version 0.76. This issue stems from the improper handling of disabled user accounts within the authentication process, creating a significant security weakness that affects systems relying on PAM for access control. The flaw specifically manifests when the system encounters a user account with a disabled password, where the authentication module fails to properly distinguish between a disabled account and an account with no password set, leading to potential unauthorized access.
The technical implementation of this vulnerability occurs at the core authentication logic level within PAM's password validation mechanisms. When a user account has its password disabled through administrative configuration, the system should reject authentication attempts regardless of the input provided. However, PAM 0.76 incorrectly processes disabled passwords by treating them as equivalent to empty password fields, allowing attackers to bypass normal authentication checks. This misconfiguration creates a privilege escalation vector where malicious actors can authenticate as disabled users, potentially gaining access to resources and permissions associated with those accounts.
The operational impact of this vulnerability extends beyond simple authentication bypass to encompass broader system security implications. Local attackers can exploit this weakness to gain unauthorized access to systems by simply attempting to authenticate as disabled users, while remote attackers may leverage this flaw in network-based authentication scenarios. The vulnerability undermines the fundamental principle of account management where disabled accounts should remain inaccessible to prevent unauthorized system access. This weakness particularly affects environments where account disabling is used as a security measure, such as during employee termination or when accounts are compromised, as the system fails to enforce the intended access restrictions.
Systems utilizing PAM 0.76 are particularly vulnerable to exploitation through various attack vectors that target the authentication subsystem. The flaw aligns with CWE-287, which addresses improper authentication issues, and can be mapped to ATT&CK technique T1078.001 for valid accounts, as attackers can effectively use disabled accounts to maintain persistent access. Organizations implementing this version of PAM should consider the broader implications for their security posture, as the vulnerability can be exploited to bypass account lockout mechanisms and other authentication controls. The impact is particularly severe in multi-user environments where disabled accounts may still retain important system permissions or access to sensitive data.
The recommended mitigation strategy involves immediate upgrading to a patched version of PAM that properly handles disabled password states. System administrators should also implement additional monitoring and logging of authentication attempts, particularly those targeting disabled accounts, to detect potential exploitation attempts. Configuration reviews should ensure that disabled accounts are properly secured and that authentication mechanisms correctly enforce account status restrictions. Organizations may need to conduct comprehensive security audits to identify any existing compromised accounts and implement proper account lifecycle management processes to prevent similar vulnerabilities in other authentication components.