CVE-2013-1952 in Xen
Summary
by MITRE
Xen 4.x, when using Intel VT-d for a bus mastering capable PCI device, does not properly check the source when accessing a bridge device s interrupt remapping table entries for MSI interrupts, which allows local guest domains to cause a denial of service (interrupt injection) via unspecified vectors.
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Analysis
by VulDB Data Team • 05/10/2021
The vulnerability described in CVE-2013-1952 affects Xen hypervisor versions 4.x that implement Intel VT-d (Virtualization Technology for Directed I/O) for PCI device access. This flaw specifically impacts systems where guest domains utilize bus mastering capable PCI devices and interrupt remapping tables for MSI (Message Signaled Interrupts). The vulnerability stems from insufficient validation of source identification when accessing bridge device interrupt remapping table entries, creating a critical security gap in the hypervisor's interrupt handling mechanisms. The issue manifests as a local privilege escalation vector that enables malicious guest domains to manipulate interrupt injection processes.
The technical implementation of this vulnerability resides in the hypervisor's interrupt remapping table validation logic within the VT-d subsystem. When a guest domain attempts to access MSI interrupt entries through a bridge device, the hypervisor fails to properly authenticate or verify the source of the access request. This validation failure allows an attacker to craft malicious interrupt injection requests that bypass normal access controls. The flaw specifically impacts the bridge device's interrupt remapping table entries, which are critical components for managing interrupt routing between hardware devices and virtual machine domains. The vulnerability operates at the hypervisor level, making it particularly dangerous as it can be exploited by any local guest domain with sufficient privileges to access PCI devices.
The operational impact of CVE-2013-1952 extends beyond simple denial of service conditions, as it fundamentally compromises the integrity of the hypervisor's interrupt handling system. Attackers can leverage this vulnerability to inject arbitrary interrupts into the system, potentially causing system instability, data corruption, or even complete system crashes. The local nature of the exploit means that any guest domain with access to PCI devices can potentially exploit this weakness, making it particularly dangerous in multi-tenant cloud environments where multiple users share the same physical hardware. The vulnerability also enables attackers to disrupt normal system operations by manipulating interrupt routing, which can affect critical system services and applications running on the host.
Mitigation strategies for this vulnerability require immediate patching of affected Xen hypervisor versions to address the interrupt remapping validation logic. System administrators should ensure that all Xen installations are updated to versions that properly validate source identification when accessing bridge device interrupt remapping table entries. The implementation of additional monitoring controls can help detect anomalous interrupt injection patterns that may indicate exploitation attempts. Organizations should also consider implementing virtual machine isolation measures that limit guest domain access to critical hardware resources, particularly those related to interrupt handling and device management. This vulnerability aligns with CWE-284 Access Control and ATT&CK technique T1068, which covers local privilege escalation and privilege abuse through hypervisor manipulation. The recommended remediation approach includes comprehensive testing of patched systems to ensure that interrupt handling functionality remains intact while preventing the specific source validation bypass that enables this attack vector.