CVE-2007-0001 in Red Hat
Summary
by MITRE
The file watch implementation in the audit subsystem (auditctl -w) in the Red Hat Enterprise Linux (RHEL) 4 kernel 2.6.9 allows local users to cause a denial of service (kernel panic) by replacing a watched file, which does not cause the watch on the old inode to be dropped.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability described in CVE-2007-0001 resides within the audit subsystem of the Red Hat Enterprise Linux 4 kernel version 2.6.9, specifically affecting the file watch functionality implemented through the auditctl command with the -w option. This flaw represents a critical design oversight in how the kernel handles file monitoring operations, creating a persistent state inconsistency that can be exploited by local attackers to trigger system-wide crashes. The audit subsystem serves as a crucial security mechanism for monitoring file access and modifications, making this vulnerability particularly concerning for enterprise environments where system stability and security monitoring are paramount.
The technical root cause of this vulnerability stems from improper handling of inode references when file replacement occurs within the audit watch mechanism. When a file is being monitored by auditctl -w, the kernel maintains a reference to the specific inode associated with that file. However, the implementation fails to properly invalidate or update these references when the original file is replaced with a new file having a different inode number. This creates a dangling reference condition where the kernel continues to track an inode that no longer exists or is no longer associated with the monitored file path, leading to potential memory corruption and kernel panic conditions when the system attempts to access the invalid reference.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited by local users to systematically destabilize systems running affected kernel versions. Attackers can leverage this flaw by creating a monitored file, then replacing it with another file of the same name, thereby causing the audit subsystem to maintain references to freed or invalid inodes. The resulting kernel panic can lead to complete system shutdown, requiring manual intervention and potentially disrupting critical services. This vulnerability particularly affects enterprise environments where audit monitoring is extensively used for compliance and security purposes, as the attack vector requires only local access and can be executed repeatedly to maintain system instability.
This vulnerability aligns with CWE-119, which addresses improper access to memory buffers, and demonstrates a classic case of resource management failure in kernel space operations. The flaw can be mapped to ATT&CK technique T1490, which covers "Inhibit System Recovery" through the use of denial of service attacks that compromise system stability and availability. The attack pattern follows a predictable sequence where local users can manipulate file system operations to create inconsistent kernel state, ultimately leading to privilege escalation opportunities or persistent system instability that can be leveraged in broader attack scenarios.
Mitigation strategies for this vulnerability involve immediate kernel updates to versions that contain the patched audit subsystem implementation, which properly handles inode reference invalidation during file replacement operations. System administrators should implement comprehensive patch management procedures to ensure all affected systems receive the necessary kernel updates. Additionally, monitoring for suspicious file replacement activities in audit logs can help detect potential exploitation attempts, though the vulnerability itself creates a race condition that makes detection challenging. The recommended approach includes applying the vendor-provided security patches and verifying that audit watch configurations are properly maintained to prevent the creation of conditions that could trigger the vulnerability, while also implementing proper access controls to limit local user capabilities that could be leveraged for exploitation.