CVE-2009-2482 in NetBSD
Summary
by MITRE
The pam_unix module in OpenPAM in NetBSD 4.0 before 4.0.2 and 5.0 before 5.0.1 allows local users to change the current root password if it is already known, even when they are not in the wheel group.
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Analysis
by VulDB Data Team • 11/18/2018
The vulnerability identified as CVE-2009-2482 represents a significant authorization flaw within the pam_unix module of OpenPAM implementation in NetBSD operating systems. This issue affects versions prior to 4.0.2 and 5.0.1, creating a dangerous privilege escalation vector that undermines the fundamental security model of Unix-like systems. The flaw specifically targets the password change functionality within the Pluggable Authentication Module framework, which is responsible for managing authentication and authorization processes across the operating system.
The technical nature of this vulnerability stems from improper access control validation within the pam_unix module's password change implementation. When a local user attempts to change the root password, the system should typically verify that the user possesses appropriate privileges through group membership verification, particularly checking for wheel group membership which traditionally grants administrative capabilities. However, this flaw allows authenticated local users to bypass these security checks when the root password is already known, effectively eliminating the need for proper authorization mechanisms. The vulnerability operates at the authentication layer, specifically targeting the password modification process where the system fails to enforce proper privilege validation.
The operational impact of this vulnerability is severe and far-reaching within compromised systems. An attacker with local access who already knows the root password can escalate their privileges without proper authorization, potentially leading to complete system compromise. This vulnerability undermines the principle of least privilege by allowing unauthorized users to assume administrative control of the system. The implications extend beyond simple privilege escalation as it can enable persistent access, data exfiltration, system modification, and complete denial of service conditions. Attackers could leverage this weakness to establish backdoors, install malware, or conduct reconnaissance activities without detection.
Security professionals should implement immediate mitigations including upgrading to NetBSD versions 4.0.2 or 5.0.1 where this vulnerability has been patched. Organizations must also conduct thorough vulnerability assessments to identify systems running affected versions and ensure proper patch management procedures are in place. The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1068, involving privilege escalation through local exploit. Additional defensive measures include implementing proper monitoring for unauthorized password change attempts, restricting local access to system administrators only, and ensuring comprehensive audit logging of authentication activities. System administrators should also consider implementing additional authentication controls such as two-factor authentication and regular privilege reviews to mitigate the risk of exploitation.
This vulnerability demonstrates the critical importance of proper access control implementation in authentication modules and highlights the potential consequences of insufficient privilege validation in security-critical system components. The flaw represents a failure in the security model's enforcement mechanisms and serves as a reminder of the need for comprehensive security testing of authentication frameworks. Organizations must maintain vigilance in monitoring for similar issues in other authentication modules and ensure that all security patches are applied promptly to protect against known vulnerabilities.