CVE-2015-3247 in SPICE
Summary
by MITRE
Race condition in the worker_update_monitors_config function in SPICE 0.12.4 allows a remote authenticated guest user to cause a denial of service (heap-based memory corruption and QEMU-KVM crash) or possibly execute arbitrary code on the host via unspecified vectors.
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Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-3247 represents a critical race condition flaw within the SPICE virtualization protocol implementation, specifically affecting version 0.12.4. This issue resides in the worker_update_monitors_config function which handles configuration updates for virtual monitor setups. The vulnerability manifests when an authenticated guest user executes malicious operations against the SPICE server, creating a scenario where concurrent access to shared memory resources can lead to unpredictable behavior. The race condition occurs during the processing of monitor configuration updates, where multiple threads or processes attempt to modify the same memory structures without proper synchronization mechanisms. This flaw is particularly dangerous in virtualized environments where guest operating systems maintain authenticated access to the SPICE server, as it enables attackers to manipulate the system state through carefully crafted sequences of configuration updates.
The technical exploitation of this vulnerability leverages the inherent timing issues in the worker_update_monitors_config function where memory allocation and deallocation occur in a non-atomic manner. When multiple monitor configuration updates are processed concurrently, the heap-based memory corruption can manifest through buffer overflows, use-after-free conditions, or double-free scenarios. The heap corruption occurs because the function fails to properly synchronize access to shared monitor configuration data structures, allowing a malicious guest user to manipulate the memory layout in ways that can cause the QEMU-KVM hypervisor to crash or potentially execute arbitrary code on the host system. The vulnerability's impact extends beyond simple denial of service as the memory corruption can be leveraged to achieve privilege escalation or code execution within the host environment, making it particularly attractive to sophisticated attackers.
The operational impact of CVE-2015-3247 in production virtualization environments is severe and multifaceted. Organizations running QEMU-KVM hypervisors with SPICE integration face significant risks including complete system outages when the vulnerability is exploited, data loss due to hypervisor crashes, and potential compromise of the entire virtualization infrastructure. The vulnerability affects any system where guest users have authenticated access to SPICE services, which includes most virtual desktop infrastructure deployments, cloud computing platforms, and remote desktop solutions. Security teams must consider that this flaw can be exploited by insiders or compromised guest users, making it particularly challenging to defend against. The vulnerability's presence in SPICE 0.12.4 means that organizations using older versions of the virtualization stack are particularly vulnerable, as the race condition exists in the core configuration update mechanism that handles monitor setup changes.
Mitigation strategies for CVE-2015-3247 should focus on immediate patching of the SPICE component to version 0.12.5 or later, where the race condition has been properly addressed through enhanced synchronization mechanisms. Organizations should implement network segmentation to restrict guest user access to SPICE services where possible, reducing the attack surface available to potential exploiters. The implementation of proper access controls and monitoring of SPICE configuration update operations can help detect anomalous behavior indicative of exploitation attempts. Security professionals should also consider disabling unnecessary SPICE features and implementing strict authentication controls to limit the scope of potential attacks. From a compliance perspective, this vulnerability aligns with CWE-362, which specifically addresses race conditions in concurrent programming, and may be mapped to ATT&CK technique T1059 for privilege escalation and T1499 for disruption of services. Organizations should conduct thorough vulnerability assessments to identify all systems running affected SPICE versions and establish monitoring procedures to detect potential exploitation attempts through abnormal memory allocation patterns or hypervisor crash reports.