CVE-2013-4311 in Red Hat
Summary
by MITRE
libvirt 1.0.5.x before 1.0.5.6, 0.10.2.x before 0.10.2.8, and 0.9.12.x before 0.9.12.2 allows local users to bypass intended access restrictions by leveraging a PolkitUnixProcess PolkitSubject race condition in pkcheck via a (1) setuid process or (2) pkexec process, a related issue to CVE-2013-4288.
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Analysis
by VulDB Data Team • 01/08/2022
The vulnerability described in CVE-2013-4311 represents a critical access control flaw within libvirt versions prior to specific patch releases, affecting the daemon's ability to properly authenticate and authorize privileged operations. This issue stems from a race condition in the PolkitUnixProcess PolkitSubject implementation, where the system fails to correctly validate process credentials during authentication checks. The flaw specifically impacts the pkcheck utility and its interaction with pkexec processes, creating opportunities for unauthorized privilege escalation. The vulnerability exists in multiple libvirt version streams including 1.0.5.x, 0.10.2.x, and 0.9.12.x, all before their respective patched releases, indicating a widespread issue affecting the core virtualization management framework. This authentication bypass allows local attackers to execute privileged operations without proper authorization, undermining the security model of the virtualization platform.
The technical exploitation of this vulnerability relies on a race condition between process creation and Polkit subject validation, where the PolkitUnixProcess object fails to properly verify the process credentials during the pkcheck authentication flow. When a setuid process or pkexec process attempts to perform privileged operations, the system's timing window allows an attacker to manipulate the authentication process by creating a malicious process that temporarily appears to have elevated privileges. The race condition occurs because the PolkitSubject validation does not properly synchronize with the actual process execution context, allowing attackers to leverage this temporal gap to bypass intended access controls. This flaw specifically affects the pkcheck utility which is responsible for checking authorization policies, making it a critical component in the privilege escalation chain. The vulnerability is classified under CWE-362, which describes Race Conditions, and represents a classic timing attack against authentication mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation to compromise the entire virtualization infrastructure managed by libvirt. Local attackers can leverage this flaw to execute arbitrary code with elevated privileges, potentially leading to complete system compromise or unauthorized access to virtual machines and their associated resources. The vulnerability affects systems where libvirt is used for managing virtual machines, containers, or other virtualized environments, making it particularly dangerous in cloud computing and data center environments. Attackers can exploit this to gain access to sensitive virtual machine configurations, data, and potentially move laterally within the network infrastructure. The vulnerability's persistence across multiple version streams indicates that organizations using libvirt for virtualization management face prolonged exposure, especially in environments where patch management processes are slow or incomplete. This makes the vulnerability particularly concerning for enterprise environments where virtualization platforms are extensively deployed.
Organizations should immediately apply the vendor patches released for libvirt versions 1.0.5.6, 0.10.2.8, and 0.9.12.2 to address this vulnerability. The patch addresses the race condition by implementing proper synchronization mechanisms in the PolkitSubject validation process, ensuring that process credentials are properly verified before authorization decisions are made. System administrators should also implement additional monitoring to detect unauthorized access attempts and privilege escalation activities, particularly focusing on pkcheck and pkexec process execution patterns. Network segmentation and privilege separation should be enforced to limit the impact of potential exploitation, while regular security assessments should be conducted to identify other potential authentication bypass vulnerabilities. The vulnerability's classification under ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', highlights the need for comprehensive endpoint protection and process monitoring to detect and prevent exploitation attempts. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across their virtualization infrastructure.