CVE-2001-1256 in HP-UX
Summary
by MITRE
kmmodreg in HP-UX 11.11, 11.04 and 11.00 allows local users to create arbitrary world-writeable files via a symlink attack on the (1) /tmp/.kmmodreg_lock and (2) /tmp/kmpath.tmp temporary files.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability identified as CVE-2001-1256 represents a critical privilege escalation flaw in HP-UX operating systems version 11.11, 11.04, and 11.00 affecting the kmmodreg component. This issue stems from insecure temporary file handling practices that create exploitable conditions for local attackers to gain elevated system privileges. The vulnerability specifically targets two temporary files located in the /tmp directory: /tmp/.kmmodreg_lock and /tmp/kmpath.tmp, which are utilized during kernel module registration processes. The flaw manifests when the system creates these temporary files without proper security checks, allowing malicious users to establish symbolic links that redirect file operations to arbitrary locations. This insecure file creation pattern directly violates security best practices and creates a path for privilege escalation attacks.
The technical exploitation of this vulnerability involves a classic symlink attack methodology where an attacker creates symbolic links to target locations before the legitimate system process attempts to create the temporary files. When kmmodreg executes and attempts to create these temporary files, it follows the symbolic links instead of creating the intended files, potentially allowing the attacker to write to world-writable locations. This type of vulnerability falls under CWE-377, which specifically addresses insecure temporary file creation practices, and represents a form of race condition attack where timing and file system permissions are manipulated. The attack vector operates at the local user level, requiring no special privileges initially but enabling privilege escalation through the manipulation of temporary file creation processes. The vulnerability is particularly dangerous because it allows attackers to create files with world-writeable permissions, potentially enabling them to modify system-critical files or inject malicious code that will execute with elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise potential. Local users who can exploit this vulnerability can potentially modify system files, install backdoors, or manipulate kernel modules to maintain persistent access. The attack requires minimal privileges initially, making it particularly attractive to attackers who may have gained access to a user account through other means. The vulnerability affects the fundamental security model of HP-UX systems by allowing unauthorized file creation in system directories, undermining the principle of least privilege. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers 'Local Privilege Escalation' and potentially T1548.001 for 'Abuse Elevation Control Mechanism'. The exploitability is enhanced by the fact that these temporary files are created in the widely accessible /tmp directory, and the race condition nature makes detection difficult. The vulnerability's persistence potential means that once exploited, attackers can maintain access even after system reboots if they establish appropriate persistence mechanisms. The impact is particularly severe on systems where the kmmodreg utility is frequently used for kernel module management, which is common in enterprise environments with dynamic kernel module loading requirements.
Mitigation strategies for CVE-2001-1256 must address both immediate patching requirements and long-term system hardening measures. The primary solution involves applying the official HP-UX patches released by Hewlett-Packard to address the insecure temporary file creation logic in kmmodreg. Organizations should also implement immediate operational controls such as restricting write access to the /tmp directory for non-root users, implementing proper file system permissions for temporary file creation, and monitoring for suspicious symbolic link creation patterns. System administrators should consider implementing mandatory access controls or discretionary access controls that prevent unauthorized users from creating symbolic links in critical temporary directories. The vulnerability also highlights the importance of regular security audits of system utilities and their temporary file handling processes. Additionally, implementing intrusion detection systems that monitor for race condition exploits and symbolic link manipulation attempts can provide early warning of potential exploitation attempts. Organizations should also consider implementing privilege separation techniques and ensuring that system utilities are not run with unnecessary elevated privileges. The remediation process should include comprehensive testing of patches to ensure they do not introduce compatibility issues with existing system configurations or kernel modules. Regular security assessments of similar system utilities should be conducted to identify and remediate other potential race condition vulnerabilities in temporary file handling processes.