CVE-2014-8136 in libvirt
Summary
by MITRE
The (1) qemuDomainMigratePerform and (2) qemuDomainMigrateFinish2 functions in qemu/qemu_driver.c in libvirt do not unlock the domain when an ACL check fails, which allow local users to cause a denial of service via unspecified vectors.
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Analysis
by VulDB Data Team • 03/02/2022
The vulnerability described in CVE-2014-8136 resides within the libvirt virtualization management library, specifically affecting the qemu driver component that manages qemu virtual machines. This issue manifests in two distinct functions: qemuDomainMigratePerform and qemuDomainMigrateFinish2, both located in the qemu/qemu_driver.c source file. The flaw represents a classic resource management error that occurs during migration operations of virtual machines within the libvirt framework, creating a potential denial of service condition that can be exploited by local attackers.
The technical root cause of this vulnerability stems from improper lock management within the migration process. When an Access Control List (ACL) check fails during domain migration operations, the functions fail to properly release the domain lock that was acquired at the beginning of the migration process. This lock remains held indefinitely, preventing any further operations on the affected domain. The issue is particularly concerning because it operates at the core level of virtual machine management where domain locks are essential for maintaining system integrity and preventing race conditions. The failure to unlock the domain creates a deadlock scenario where the domain becomes permanently inaccessible to both legitimate administrative operations and normal virtual machine functions.
From an operational perspective, this vulnerability presents a significant risk to virtualized environments where local users may have limited privileges but can still execute migration commands. The denial of service impact means that once exploited, the affected virtual machine domain becomes completely unresponsive to any management commands, effectively rendering it unusable within the virtualization infrastructure. Attackers can leverage this vulnerability to disrupt services, cause system instability, or potentially escalate their privileges if they can manipulate the migration process to target critical domains. The vulnerability's local nature means that exploitation does not require network access, making it particularly dangerous in multi-tenant virtualization environments where local access might be granted to untrusted users.
The implications of this vulnerability align with several cybersecurity frameworks and threat modeling approaches. From the Common Weakness Enumeration perspective, this represents a weakness categorized under CWE-665 Improper Initialization, specifically related to improper resource management and lock handling. The ATT&CK framework would classify this vulnerability under T1499.004 Compromise of Virtualization and Container Resources, where adversaries can manipulate system resources to cause denial of service conditions. Additionally, this vulnerability demonstrates characteristics of T1068 Exploitation for Privilege Escalation, as local users may be able to leverage the lock contention to gain further access to the system. The issue also connects to T1566.001 Phishing with Social Engineering, as attackers might use this vulnerability in conjunction with social engineering tactics to target specific virtual machine domains.
Mitigation strategies for this vulnerability should focus on immediate code-level fixes that ensure proper lock management during ACL check failures. The primary solution involves implementing proper error handling that releases all acquired locks when ACL checks fail, regardless of the specific failure reason. System administrators should prioritize updating to patched versions of libvirt that address this specific locking mechanism issue. Additionally, implementing monitoring systems to detect unusual lock patterns or prolonged domain unavailability can help identify potential exploitation attempts. Network segmentation and privilege separation should be enforced to limit local access to virtualization management interfaces, reducing the attack surface. Regular security audits of virtualization infrastructure should include checks for similar lock management issues, as this represents a common pattern in resource management vulnerabilities that can lead to similar denial of service conditions.