CVE-2012-6035 in Xen
Summary
by MITRE
The do_tmem_destroy_pool function in the Transcendent Memory (TMEM) in Xen 4.0, 4.1, and 4.2 does not properly validate pool ids, which allows local guest OS users to cause a denial of service (memory corruption and host crash) or execute arbitrary code via unspecified vectors. 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-2012-6035 resides within the Transcendent Memory (TMEM) subsystem of the Xen hypervisor version 4.0, 4.1, and 4.2. This flaw manifests in the do_tmem_destroy_pool function which fails to properly validate pool identifiers, creating a critical security gap that can be exploited by local users within guest operating systems. The improper validation occurs at the hypervisor level where guest users can manipulate pool identifiers to trigger unexpected behavior in the memory management system. This vulnerability represents a classic case of insufficient input validation that can lead to privilege escalation and system compromise.
The technical implementation of this flaw stems from the lack of proper bounds checking and validation within the TMEM subsystem's pool destruction mechanism. When guest operating systems attempt to destroy memory pools through the do_tmem_destroy_pool function, the hypervisor fails to verify the legitimacy of the pool identifiers provided by the guest. This validation gap creates opportunities for attackers to craft malicious pool identifiers that can cause memory corruption within the hypervisor's address space. The vulnerability operates at the kernel level where guest users can leverage this weakness to execute arbitrary code or induce memory corruption that ultimately results in system crashes. This issue falls under CWE-129, which specifically addresses insufficient validation of length of input buffers, and represents a type of buffer overflow vulnerability that can be exploited for privilege escalation.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include potential arbitrary code execution within the host system. Local guest users can exploit this weakness to corrupt memory structures used by the hypervisor, leading to unpredictable behavior including system crashes, data corruption, or in severe cases, complete system compromise. The vulnerability affects multiple versions of Xen, making it particularly dangerous as it impacts a wide range of virtualized environments. Attackers can leverage this flaw to escalate privileges from guest user level to host level execution, effectively breaking the isolation guarantees that virtualization provides. This represents a significant threat to cloud computing environments and any infrastructure relying on Xen hypervisors for virtual machine management.
Mitigation strategies for CVE-2012-6035 require immediate patching of affected Xen versions to address the improper pool id validation. System administrators should implement the latest security updates from Xen Project, as these patches contain proper validation mechanisms for pool identifiers. Additionally, monitoring for anomalous memory pool destruction activities within virtualized environments can help detect exploitation attempts. Network segmentation and access controls should be implemented to limit guest user privileges and reduce the attack surface. The vulnerability demonstrates the importance of proper input validation in hypervisor components and aligns with ATT&CK technique T1055 for privilege escalation through hypervisor manipulation. Organizations should also consider implementing hypervisor-level monitoring and logging to detect potential exploitation attempts and maintain audit trails for forensic analysis.