CVE-2013-1766 in libvirt
Summary
by MITRE
libvirt 1.0.2 and earlier sets the group owner to kvm for device files, which allows local users to write to these files via unspecified vectors.
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Analysis
by VulDB Data Team • 01/01/2022
The vulnerability identified as CVE-2013-1766 affects libvirt versions 1.0.2 and earlier, representing a significant security flaw in virtualization management software. This issue stems from improper privilege management within the libvirt daemon's handling of device files, where the software assigns group ownership to the kvm group for device files. The vulnerability creates a path for local privilege escalation by allowing unauthorized users to write to device files that should normally be restricted to privileged operations. This flaw operates at the kernel-level interface between virtualization software and hardware resources, making it particularly dangerous in environments where multiple users share the same host system.
The technical implementation of this vulnerability involves libvirt's device file management subsystem where device nodes are created with group permissions set to kvm. When local users belong to the kvm group or can somehow gain membership, they can exploit this misconfiguration to write to device files that typically require root privileges or specific security contexts. The unspecified vectors mentioned in the description suggest that multiple attack paths may exist, potentially including race conditions, privilege escalation techniques, or manipulation of device file descriptors. This vulnerability aligns with CWE-276, which covers improper file permissions and inadequate access control mechanisms, and represents a classic case of privilege escalation through improper access control.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it can enable attackers to manipulate virtualization resources, potentially leading to complete system compromise. In virtualized environments, this flaw allows local users to write to device files that may be used for communication with hypervisor components, storage devices, or network interfaces. Attackers could leverage this access to modify device behavior, inject malicious code, or create persistent backdoors within the virtualization infrastructure. The vulnerability particularly affects systems running libvirt for managing virtual machines, containers, or other virtualized resources where device file access is critical for system functionality. This flaw can be exploited by malicious users who gain access to a system with normal user privileges, making it a significant concern for multi-tenant environments and shared hosting platforms.
Mitigation strategies for CVE-2013-1766 require immediate patching of libvirt installations to versions 1.0.3 or later, where the improper group ownership issue has been addressed. System administrators should also implement additional security measures including regular access control audits, monitoring for unauthorized device file modifications, and ensuring proper user privilege management. The fix typically involves correcting the group ownership assignments for device files to use more restrictive permissions and proper security contexts. Organizations should consider implementing principle of least privilege for kvm group membership, ensuring that only necessary users have access to virtualization device files. This vulnerability demonstrates the importance of proper access control mechanisms in virtualization platforms and aligns with ATT&CK technique T1068, which covers privilege escalation through local system exploitation. Additionally, security frameworks such as CIS Benchmarks recommend regular configuration audits of virtualization management software to prevent similar issues from arising in production environments.