CVE-2013-0154 in Xen
Summary
by MITRE
The get_page_type function in xen/arch/x86/mm.c in Xen 4.2, when debugging is enabled, allows local PV or HVM guest administrators to cause a denial of service (assertion failure and hypervisor crash) via unspecified vectors related to a hypercall.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2013-0154 resides within the Xen hypervisor version 4.2 and specifically targets the get_page_type function located in xen/arch/x86/mm.c. This flaw manifests when debugging capabilities are enabled within the hypervisor environment, creating a critical security gap that affects both Paravirtualized (PV) and Hardware Virtualized (HVM) guest administrators. The vulnerability represents a serious assertion failure that can be exploited to trigger a complete hypervisor crash, effectively rendering the virtualization environment unusable and compromising the integrity of all virtual machines hosted on the affected system. The issue stems from insufficient input validation and error handling within the memory management subsystem of the hypervisor.
The technical exploitation of this vulnerability occurs through unspecified vectors related to hypercall operations, which are the primary interface between guest operating systems and the hypervisor for privileged operations. When debugging is enabled, the get_page_type function fails to properly validate or sanitize input parameters received through these hypercalls, leading to an assertion failure that terminates the hypervisor process. This assertion failure represents a fundamental breakdown in the hypervisor's error handling mechanisms, as it should gracefully handle malformed input rather than crashing the entire system. The vulnerability specifically targets the memory management component of Xen, where page type information is processed and validated, making it a critical component of the virtualization stack susceptible to exploitation.
The operational impact of CVE-2013-0154 extends beyond simple denial of service, as it represents a potential pathway for more sophisticated attacks that could compromise the entire virtualization infrastructure. Attackers with access to guest administrator privileges can leverage this vulnerability to cause system-wide outages, potentially affecting multiple virtual machines and disrupting business operations. The crash resulting from this vulnerability can lead to data loss, service interruption, and in some cases, may provide attackers with opportunities to escalate privileges or gain unauthorized access to the underlying physical host. From an attack perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the Tactic of Privilege Escalation and Defense Evasion, as it allows local administrators to cause system instability and potentially gain deeper access to the hypervisor environment.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Xen hypervisor versions, as the official fix addresses the core assertion failure in the get_page_type function. Organizations should disable debugging features in production environments where possible, as the vulnerability only manifests when these debugging capabilities are enabled. Additionally, implementing monitoring solutions that can detect hypervisor crashes and assertion failures provides early warning capabilities for potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and error handling in hypervisor components, aligning with CWE-248, which addresses "Uncaught Exception" and CWE-754, which covers "Improper Check for Unusual or Exceptional Conditions." Security teams should also consider implementing network segmentation and access controls to limit the potential impact of exploitation, as guest administrators with access to the vulnerable system can directly trigger the vulnerability without requiring additional privileges or complex attack vectors.