CVE-2008-2382 in KVM
Summary
by MITRE
The protocol_client_msg function in vnc.c in the VNC server in (1) Qemu 0.9.1 and earlier and (2) KVM kvm-79 and earlier allows remote attackers to cause a denial of service (infinite loop) via a certain message.
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Analysis
by VulDB Data Team • 12/24/2024
The vulnerability identified as CVE-2008-2382 represents a critical denial of service flaw within the Virtual Network Computing implementation of QEMU and KVM virtualization platforms. This vulnerability resides in the protocol_client_msg function located within the vnc.c file of the VNC server component, affecting versions of QEMU prior to 0.9.1 and KVM versions up to kvm-79. The flaw manifests when the VNC server processes specific malformed messages from remote clients, creating a condition that leads to an infinite loop within the server's message handling routine.
The technical nature of this vulnerability stems from inadequate input validation and message processing within the VNC protocol implementation. When a remote attacker sends a specially crafted message to the VNC server, the protocol_client_msg function fails to properly validate the message structure or content, allowing the server to enter an infinite loop during message processing. This infinite loop consumes excessive CPU resources and effectively renders the VNC server unavailable to legitimate users, creating a denial of service condition that can persist until the server is manually restarted or the malicious connection is terminated.
From an operational impact perspective, this vulnerability poses significant risks to virtualized environments where VNC access is enabled for remote management or debugging purposes. The vulnerability can be exploited by any remote attacker with network access to the affected VNC server, making it particularly dangerous in cloud computing environments or any infrastructure where VNC services are exposed to untrusted networks. The infinite loop condition not only affects the specific VNC service but can also impact the overall system performance and availability, potentially affecting other services running on the same host system. This vulnerability aligns with CWE-835, which addresses infinite loops or iterations without proper termination conditions, and represents a classic example of how protocol implementation flaws can lead to denial of service conditions.
The exploitation of this vulnerability demonstrates the importance of proper input validation in network services and highlights the risks associated with legacy VNC implementations in virtualization platforms. Organizations using affected versions of QEMU or KVM should prioritize immediate patching to address this vulnerability, as the denial of service condition can be easily triggered without requiring authentication or special privileges. The vulnerability also underscores the need for robust security testing of protocol implementations, particularly in widely deployed virtualization software where such flaws can have widespread impact across numerous systems and deployments.
Security practitioners should consider this vulnerability in the context of the ATT&CK framework, specifically under the T1499 category of Network Denial of Service, where adversaries can leverage protocol implementation flaws to disrupt services. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date virtualization software and implementing proper network segmentation to limit exposure of VNC services to untrusted networks. Additionally, organizations should implement monitoring solutions to detect abnormal CPU usage patterns that might indicate exploitation of this vulnerability, as the infinite loop condition creates distinctive performance signatures that can be used for detection purposes.