CVE-2011-0637 in AIX
Summary
by MITRE
The FC SCSI protocol driver in IBM AIX 6.1 does not verify that a timer is unused before deallocating this timer, which might allow attackers to cause a denial of service (system crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 04/13/2019
The vulnerability identified as CVE-2011-0637 resides within the Fibre Channel SCSI protocol driver implementation in IBM AIX 6.1 operating systems. This flaw represents a classic resource management error that occurs during the deallocation phase of system timer objects. The core issue manifests when the driver fails to validate whether a timer resource is actively in use before proceeding with its deallocation process. Such improper resource handling creates a potential race condition scenario where concurrent access patterns could lead to undefined behavior during system operation. The vulnerability operates at the kernel level within the storage subsystem, specifically targeting the FC SCSI protocol implementation that manages fibre channel communications for storage devices. This type of flaw typically arises from insufficient state validation mechanisms within the driver's memory management routines, where proper synchronization and resource status checks are not adequately enforced. The absence of proper timer validation creates a window of opportunity for malicious actors to exploit the system's resource cleanup procedures.
The technical exploitation of this vulnerability leverages the improper timer deallocation mechanism to trigger system instability. When an attacker can manipulate the timing or sequence of operations that lead to timer deallocation, they may be able to force the system into a state where memory corruption or invalid memory access occurs. This particular flaw falls under the category of improper deallocation issues that are commonly classified as CWE-415, which deals with double free conditions and improper resource deallocation. The vulnerability's impact extends beyond simple denial of service to potentially compromise system stability and availability, as the FC SCSI driver is critical for storage operations in enterprise environments. The unspecified vectors mentioned in the description suggest that multiple attack paths may exist, potentially including crafted storage commands or specific timing sequences that trigger the problematic code path. Attackers could potentially leverage this vulnerability to cause system crashes or reboot cycles, effectively rendering the system unavailable to legitimate users while maintaining operational control over the storage infrastructure.
The operational impact of CVE-2011-0637 extends significantly within enterprise computing environments that rely on IBM AIX 6.1 systems for mission-critical storage operations. Organizations utilizing fibre channel storage architectures face potential disruption to their data services when this vulnerability is exploited, as the FC SCSI driver manages communications between storage devices and the operating system. The vulnerability's potential to cause system crashes directly impacts business continuity and data availability, particularly in environments where storage reliability is paramount. From an attack perspective, this vulnerability aligns with techniques described in the attack pattern taxonomy under ATT&CK framework category T1499, which covers network denial of service attacks and system resource exhaustion. The flaw represents a low-effort, high-impact vector for adversaries seeking to disrupt storage services, as it requires minimal specialized knowledge to potentially exploit. System administrators must consider the broader implications for their storage infrastructure, as this vulnerability could be leveraged as part of a larger attack chain targeting storage systems. The vulnerability's presence in AIX 6.1 systems indicates a need for careful patch management and monitoring of storage-related system calls and driver behaviors.
Mitigation strategies for CVE-2011-0637 should prioritize immediate patch deployment from IBM, as the vendor has likely provided specific fixes for this timer deallocation issue. Organizations should implement comprehensive monitoring of system stability metrics and storage subsystem performance to detect potential exploitation attempts. The recommended approach includes establishing baseline system behavior patterns and implementing anomaly detection for storage driver operations. Security teams should conduct thorough vulnerability assessments of their AIX environments to identify systems running version 6.1 that may be affected by this issue. Additional defensive measures include restricting access to storage management interfaces and implementing proper access controls for fibre channel communications. System hardening practices should emphasize proper resource management and memory validation within kernel modules. The vulnerability's nature suggests that proper code review and testing of resource deallocation routines would prevent similar issues in future implementations. Organizations should also consider implementing redundant storage paths and backup systems to maintain availability during potential exploitation events. Regular security audits of kernel modules and driver implementations remain essential for identifying similar resource management flaws that could lead to system instability or compromise.