CVE-2012-6030 in Xen
Summary
by MITRE
The do_tmem_op function in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 allow local guest OS users to cause a denial of service (host crash) and possibly have other unspecified impacts via unspecified vectors related to "broken locking checks" in an "error path." NOTE: this issue was originally published as part of CVE-2012-3497, which was too general; CVE-2012-3497 has been SPLIT into this ID and others.
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Analysis
by VulDB Data Team • 12/20/2021
The vulnerability described in CVE-2012-6030 resides within the Transcendent Memory (TMEM) subsystem of the Xen hypervisor version 4.0, 4.1, and 4.2. This issue specifically targets the do_tmem_op function which handles operations related to transcendent memory management. The flaw manifests as a critical security weakness that allows local users within guest operating systems to exploit broken locking mechanisms during error handling paths. The vulnerability represents a significant concern for virtualization environments since it enables privilege escalation from guest level to host level compromise, potentially leading to complete system compromise.
The technical flaw stems from improper locking checks within the error handling pathways of the TMEM subsystem. When the do_tmem_op function encounters an error condition, it fails to properly validate or acquire necessary locks before proceeding with cleanup operations. This broken locking mechanism creates a race condition scenario where concurrent access to shared memory structures can result in memory corruption. The vulnerability is particularly dangerous because it operates within the hypervisor's memory management layer, making it difficult to detect and exploit. According to CWE classification, this corresponds to CWE-362, which addresses race conditions in concurrent programming, and CWE-121, which deals with stack-based buffer overflow conditions. The improper locking checks create a scenario where multiple threads or processes can access protected resources simultaneously, leading to unpredictable behavior and potential system crashes.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more severe compromise scenarios. Local guest users can trigger host crashes that result in complete system downtime, affecting all virtual machines running on the compromised hypervisor. This vulnerability is particularly concerning in cloud computing environments where multiple tenants share the same physical infrastructure, as it allows one tenant to potentially disrupt services for other tenants. The unspecified additional impacts mentioned in the description suggest that beyond simple DoS, this vulnerability could potentially enable privilege escalation or information disclosure. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers 'Exploitation for Privilege Escalation,' and T1499, which addresses 'Endpoint Denial of Service.' The vulnerability essentially provides a pathway for guest users to escalate their privileges and gain access to host-level resources, undermining the fundamental security isolation that hypervisors are designed to provide.
Mitigation strategies for CVE-2012-6030 require immediate patching of affected Xen hypervisor versions, as the vulnerability exists in versions 4.0, 4.1, and 4.2. Organizations should implement comprehensive monitoring for any signs of exploitation attempts and establish robust incident response procedures. The fix involves correcting the locking mechanisms within the TMEM subsystem's error handling paths to ensure proper synchronization when accessing shared resources. System administrators should also consider implementing additional security controls such as hypervisor hardening measures and network segmentation to limit potential attack surface. Regular vulnerability assessments and security audits should be conducted to identify similar issues in other hypervisor components. The remediation process requires careful testing to ensure that patches do not introduce compatibility issues with existing virtualized applications and services. Organizations should also review their virtualization security policies and ensure that guest operating systems are properly isolated and monitored for suspicious activities that might indicate exploitation attempts.