CVE-2012-4423 in libvirt
Summary
by MITRE
The virNetServerProgramDispatchCall function in libvirt before 0.10.2 allows remote attackers to cause a denial of service (NULL pointer dereference and segmentation fault) via an RPC call with (1) an event as the RPC number or (2) an RPC number whose value is in a "gap" in the RPC dispatch table.
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Analysis
by VulDB Data Team • 12/20/2021
The vulnerability identified as CVE-2012-4423 represents a critical denial of service flaw within the libvirt virtualization management library. This issue affects versions prior to 0.10.2 and stems from improper handling of remote procedure calls within the virNetServerProgramDispatchCall function. The vulnerability manifests when remote attackers submit specially crafted RPC calls that exploit weaknesses in the dispatch table mechanism used by libvirt to process incoming network requests. The flaw creates a scenario where the application fails to properly validate RPC numbers before attempting to process them, leading to unpredictable behavior in the virtualization management infrastructure.
The technical implementation of this vulnerability involves two distinct attack vectors that both result in system instability. The first vector occurs when an attacker submits an RPC call with an event as the RPC number, while the second vector exploits gaps within the RPC dispatch table where RPC numbers exist but have no corresponding handler functions. These gaps create NULL pointer dereference conditions that ultimately result in segmentation faults and system crashes. The vulnerability specifically targets the network server component of libvirt, which serves as the communication interface for remote management of virtual machines and hypervisor resources. This flaw operates at the protocol level, making it particularly dangerous as it can be exploited by unauthorized remote users without requiring local system access or elevated privileges.
The operational impact of CVE-2012-4423 extends beyond simple service disruption to potentially compromise entire virtualization environments. When exploited successfully, the vulnerability can cause complete system crashes of libvirt daemon processes, leading to loss of virtual machine management capabilities and potential data integrity issues. Organizations relying on libvirt for virtualization management face significant operational risks as this vulnerability can be leveraged to deny service to legitimate users while maintaining the ability to perform other attacks against the underlying virtualization infrastructure. The vulnerability also creates opportunities for attackers to escalate their privileges or gain additional system access through cascading effects of the denial of service condition. This weakness particularly affects cloud computing environments and data centers where libvirt serves as the primary management interface for virtual machine orchestration and resource allocation.
Mitigation strategies for CVE-2012-4423 primarily focus on immediate version upgrades to libvirt 0.10.2 or later, which contain patches addressing the RPC dispatch table validation issues. System administrators should also implement network-level controls to restrict access to libvirt management interfaces, particularly when remote access is not strictly required for operations. The vulnerability demonstrates the importance of proper input validation and robust error handling in network services, aligning with CWE-476 which addresses NULL pointer dereference conditions. Organizations should also consider implementing intrusion detection systems to monitor for suspicious RPC call patterns and establish regular vulnerability assessment procedures to identify similar weaknesses in their virtualization infrastructure. Additionally, the use of network segmentation and access control lists can help limit the potential impact of successful exploitation attempts while maintaining operational functionality of legitimate management interfaces.