CVE-2001-1147 in util-linux
Summary
by MITRE
The PAM implementation in /bin/login of the util-linux package before 2.11 causes a password entry to be rewritten across multiple PAM calls, which could provide the credentials of one user to a different user, when used in certain PAM modules such as pam_limits.
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Analysis
by VulDB Data Team • 06/10/2024
The vulnerability identified as CVE-2001-1147 represents a critical flaw in the pluggable authentication modules implementation within the util-linux package's login utility. This issue specifically affects systems where the PAM framework is utilized for authentication purposes, creating a scenario where authentication credentials can be inadvertently exposed between different user sessions. The flaw manifests in the way the login program handles password entry across multiple PAM calls, fundamentally compromising the security boundaries that should exist between individual user authentication processes.
The technical root cause of this vulnerability lies in the improper handling of password data within the PAM authentication flow. When the login utility processes authentication requests through multiple PAM modules, the password entry mechanism fails to properly isolate or clear credential data between successive authentication calls. This behavior creates a condition where the password entered by one user can persist and be accessible to subsequent authentication attempts, particularly when certain PAM modules like pam_limits are in use. The vulnerability operates at the intersection of authentication state management and memory handling within the PAM framework, where proper data isolation mechanisms are not properly enforced.
The operational impact of this vulnerability extends beyond simple credential leakage to encompass potential privilege escalation and unauthorized system access. An attacker who can exploit this vulnerability may gain access to another user's credentials simply by observing or manipulating the authentication process, particularly in environments where multiple users share the same system or where PAM modules are configured to maintain state information. This flaw particularly affects systems where pam_limits is deployed, as this module's behavior can amplify the exposure by maintaining persistent authentication state information. The vulnerability creates an attack surface that allows for unauthorized credential harvesting, potentially enabling lateral movement within a network or system compromise.
From a cybersecurity perspective, this vulnerability aligns with CWE-200, which addresses information exposure, and demonstrates characteristics consistent with attack patterns found in the MITRE ATT&CK framework under credential access and privilege escalation techniques. The flaw represents a classic case of insufficient input validation and improper handling of sensitive data within authentication contexts. Organizations utilizing affected versions of util-linux should prioritize immediate patching to address this vulnerability, as the exposure duration and potential for credential compromise can persist across multiple authentication sessions. The recommended mitigation involves updating to util-linux version 2.11 or later, which includes proper handling of PAM authentication state and ensures that password data is appropriately isolated between authentication calls. Additionally, system administrators should review PAM module configurations to ensure that modules like pam_limits are properly configured and that authentication contexts are properly separated to minimize the attack surface.