CVE-2014-7154 in Xen
Summary
by MITRE
Race condition in HVMOP_track_dirty_vram in Xen 4.0.0 through 4.4.x does not ensure possession of the guarding lock for dirty video RAM tracking, which allows certain local guest domains to cause a denial of service via unspecified vectors.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/29/2022
The vulnerability identified as CVE-2014-7154 represents a critical race condition within the Xen hypervisor's HVMOP_track_dirty_vram operation, affecting versions 4.0.0 through 4.4.x. This flaw exists in the hypervisor's handling of dirty video RAM tracking mechanisms, which are essential for virtual machine memory management and graphics acceleration. The race condition specifically occurs when the hypervisor fails to properly enforce lock acquisition before processing dirty video RAM tracking operations, creating a window where malicious guest domains can exploit this weakness to disrupt system operations.
The technical implementation of this vulnerability stems from insufficient synchronization mechanisms within the hypervisor's memory tracking subsystem. When guest domains attempt to track dirty video RAM pages, the hypervisor's locking mechanism does not guarantee exclusive access to the guarding lock, allowing concurrent access patterns that can lead to inconsistent memory state tracking. This race condition manifests as a failure in maintaining proper memory access controls during the dirty page tracking process, where the hypervisor's internal data structures become corrupted or improperly updated due to concurrent modifications.
From an operational impact perspective, this vulnerability enables local guest domains to potentially cause denial of service conditions within the Xen hypervisor environment. The unspecified vectors of exploitation suggest that attackers can leverage this race condition to disrupt normal system operations, potentially leading to system instability, guest domain crashes, or complete hypervisor failure. The vulnerability is particularly concerning because it affects the core memory management functionality that underpins all virtual machine operations, making it a critical weakness in virtualized environments where multiple domains share the same physical hardware resources.
The flaw aligns with CWE-362, which categorizes race conditions in concurrent programming environments, specifically highlighting the improper handling of shared resources without proper synchronization mechanisms. This vulnerability also maps to ATT&CK technique T1499.004, which covers network denial of service attacks through hypervisor manipulation, as malicious guest domains can effectively attack the underlying virtualization infrastructure. The security implications extend beyond simple denial of service, as this weakness could potentially be chained with other vulnerabilities to escalate privileges or compromise the integrity of the entire virtualized environment.
Mitigation strategies for CVE-2014-7154 primarily focus on implementing proper lock acquisition mechanisms within the hypervisor's memory tracking subsystem. System administrators should immediately upgrade to Xen versions 4.5.0 or later, where this race condition has been addressed through enhanced synchronization protocols. Additionally, implementing proper access controls and monitoring for unusual memory tracking patterns can help detect potential exploitation attempts. Organizations should also consider isolating critical domains and implementing stricter resource allocation policies to limit the impact of potential exploitation. The fix typically involves ensuring that all dirty video RAM tracking operations properly acquire and release guarding locks before and after processing, preventing concurrent access that could lead to the race condition.