CVE-2013-0151 in Xen
Summary
by MITRE
The do_hvm_op function in xen/arch/x86/hvm/hvm.c in Xen 4.2.x on the x86_32 platform does not prevent HVM_PARAM_NESTEDHVM (aka nested virtualization) operations, which allows guest OS users to cause a denial of service (long-duration page mappings and host OS crash) by leveraging administrative access to an HVM guest in a domain with a large number of VCPUs.
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Analysis
by VulDB Data Team • 04/22/2021
The vulnerability identified as CVE-2013-0151 represents a critical flaw in the Xen hypervisor implementation that specifically affects the x86_32 platform in version 4.2.x. This issue stems from the do_hvm_op function within the hypervisor's hardware virtual machine management code, where insufficient access controls prevent proper enforcement of nested virtualization operations. The flaw occurs when guest operating systems with administrative privileges attempt to manipulate HVM_PARAM_NESTEDHVM parameters, creating a pathway for malicious or unintended behavior that can severely impact system stability and availability.
The technical root cause of this vulnerability lies in the improper validation of hypercall parameters within the hypervisor's HVM operations handler. When a guest OS with administrative access attempts to perform nested virtualization operations, the do_hvm_op function fails to properly restrict or validate these requests, particularly concerning the HVM_PARAM_NESTEDHVM parameter. This oversight allows the guest to manipulate page mappings in ways that were not intended by the hypervisor design, leading to long-duration page mappings that can persist far beyond normal operational parameters. The vulnerability specifically manifests when dealing with domains containing a large number of virtual CPUs, where the impact of improper page mapping becomes exponentially more severe.
The operational impact of this vulnerability extends beyond simple denial of service to potentially catastrophic system failure scenarios. Attackers with guest administrative privileges can leverage this flaw to create persistent page mappings that consume significant system resources and can ultimately lead to complete host OS crashes. The long-duration page mappings created through this vulnerability can cause memory exhaustion, system instability, and complete system hangs that require manual intervention to resolve. This makes the vulnerability particularly dangerous in production environments where system uptime and reliability are critical factors, as it can be exploited to create sustained service disruptions without requiring elevated privileges beyond what is already available to guest administrators.
This vulnerability aligns with CWE-284, which addresses inadequate access control mechanisms in software systems, and demonstrates how improper privilege validation can lead to severe system compromise. From an ATT&CK framework perspective, this represents a privilege escalation and denial of service technique that can be leveraged to compromise system availability. The vulnerability also relates to CWE-362, which covers concurrent execution use of a resource, as the improper page mapping operations can create race conditions and resource contention issues within the hypervisor. Organizations utilizing Xen hypervisors in virtualized environments should consider this vulnerability as part of their broader security posture assessment, particularly in scenarios involving multi-tenant deployments where guest isolation is paramount.
The recommended mitigations for CVE-2013-0151 include immediate patching of affected Xen hypervisor versions to 4.2.2 or later, where the vulnerability has been properly addressed through enhanced parameter validation and access control enforcement. System administrators should also implement monitoring solutions to detect unusual page mapping patterns and establish strict access controls for guest operating systems, particularly limiting administrative privileges in virtualized environments. Additionally, organizations should consider implementing domain-level resource limits and monitoring to prevent any single guest from consuming excessive system resources through malicious or unintended page mapping operations. Regular security assessments and vulnerability scanning should be conducted to ensure that similar issues do not exist in other hypervisor components or related systems within the virtualized infrastructure.