CVE-2013-0152 in Xen
Summary
by MITRE
Memory leak in Xen 4.2 and unstable allows local HVM guests to cause a denial of service (host memory consumption) by performing nested virtualization in a way that triggers errors that are not properly handled.
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Analysis
by VulDB Data Team • 04/22/2021
The vulnerability identified as CVE-2013-0152 represents a critical memory management flaw within the Xen hypervisor version 4.2 and its unstable branches. This issue specifically affects local HVM (Hardware Virtual Machine) guests that engage in nested virtualization activities, creating a scenario where malicious or faulty guest operating systems can exploit improper error handling mechanisms to consume excessive host memory resources. The vulnerability stems from the hypervisor's inadequate management of memory allocation during nested virtualization operations, particularly when error conditions occur during the process of creating or managing virtual machine instances within virtual machine instances.
The technical implementation of this vulnerability involves the hypervisor's failure to properly release memory resources when nested virtualization operations encounter errors. When an HVM guest attempts to perform nested virtualization and the operation fails, the memory allocated for the nested virtualization context is not properly deallocated, leading to progressive memory consumption on the host system. This memory leak occurs because the hypervisor's error handling routines do not account for all possible failure scenarios during nested virtualization, particularly those involving malformed or malicious virtualization requests that trigger unexpected error paths within the hypervisor's memory management subsystem.
The operational impact of CVE-2013-0152 extends beyond simple resource exhaustion, as it enables a local attacker within an HVM guest to systematically consume host memory resources until the system becomes unresponsive or crashes entirely. This denial of service condition can be particularly devastating in multi-tenant environments where multiple virtual machines share the same physical host, as a single compromised or malicious guest could potentially destabilize the entire hosting infrastructure. The vulnerability is classified under CWE-401 as a failure to release memory resources, and it aligns with ATT&CK technique T1499.001 for resource exhaustion attacks, making it a significant concern for cloud service providers and virtualization administrators.
Mitigation strategies for this vulnerability require immediate patching of affected Xen installations to version 4.3 or later, where the memory leak has been addressed through improved error handling and memory management routines. Administrators should also implement monitoring systems to detect unusual memory consumption patterns in hypervisor environments, particularly during nested virtualization operations. Additional protective measures include restricting nested virtualization capabilities for untrusted guests, implementing resource limits and quotas for virtual machines, and maintaining regular security updates for all virtualization infrastructure components. The fix implemented by Xen developers involved strengthening the error handling mechanisms within the nested virtualization code paths to ensure proper memory deallocation regardless of error conditions, thereby preventing the accumulation of leaked memory resources that could lead to system instability.