CVE-2001-0787 in LPRng
Summary
by MITRE
LPRng in Red Hat Linux 7.0 and 7.1 does not properly drop memberships in supplemental groups when lowering privileges, which could allow a local user to elevate privileges.
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Analysis
by VulDB Data Team • 01/13/2025
The vulnerability described in CVE-2001-0787 affects LPRng print server software distributed with Red Hat Linux 7.0 and 7.1 systems. This represents a critical privilege escalation flaw that exploits improper privilege management during process execution. The issue stems from the LPRng service's failure to correctly handle group membership when transitioning from elevated to restricted privileges, creating a persistent security weakness that local attackers can leverage for unauthorized system access.
The technical root cause of this vulnerability lies in the improper implementation of privilege dropping mechanisms within the LPRng daemon. When the service executes with elevated privileges to perform its printing functions, it should properly drop all supplemental group memberships before reducing its privilege level to that of a regular user. However, the flawed implementation maintains certain group memberships that grant access to system resources or capabilities beyond what a standard user account should possess. This behavior creates a persistent vector for privilege escalation attacks where an attacker can exploit the retained group memberships to gain elevated system access.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise possibilities. Attackers with local access can leverage the retained group memberships to access restricted files, execute privileged operations, or manipulate system resources that should normally be protected from regular user accounts. This vulnerability specifically aligns with CWE-272, which addresses "Least Privilege" issues where software fails to properly drop privileges after performing privileged operations. The flaw creates a persistent security boundary violation that undermines the fundamental principle of least privilege in system security design.
From an attack perspective, this vulnerability demonstrates a classic privilege escalation pattern that follows the ATT&CK framework's privilege escalation tactics. The local user can exploit the improper privilege management to gain elevated system privileges without requiring additional authentication or complex attack vectors. The vulnerability affects systems running Red Hat Linux 7.0 and 7.1, making it particularly concerning for organizations that may have legacy systems still operating with these older distributions. The flaw represents a failure in the Unix security model where process privilege management should ensure complete separation between privileged and unprivileged execution contexts.
Mitigation strategies for this vulnerability require immediate system updates and patch management to address the underlying privilege handling implementation. Organizations should apply the vendor-provided security patches that correct the group membership handling during privilege dropping operations. System administrators should also conduct comprehensive security audits to identify any other services or applications that may exhibit similar privilege management flaws. Additionally, implementing proper monitoring and logging of privilege transitions can help detect exploitation attempts and provide forensic evidence of security incidents. The vulnerability underscores the importance of rigorous security testing for privilege management code and the need for comprehensive security reviews of system services that handle elevated privileges during normal operation.