CVE-2017-8309 in QEMU
Summary
by MITRE
Memory leak in the audio/audio.c in QEMU (aka Quick Emulator) allows remote attackers to cause a denial of service (memory consumption) by repeatedly starting and stopping audio capture.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2017-8309 represents a critical memory management flaw within the QEMU virtualization platform that specifically affects the audio subsystem implementation. This issue resides in the audio/audio.c component of QEMU, a widely used open-source emulator that enables users to run multiple operating systems simultaneously on a single physical machine. The vulnerability manifests when the audio capture functionality is repeatedly activated and deactivated, leading to a progressive accumulation of memory resources that are not properly released back to the system. This memory leak occurs within the context of virtual machine audio handling, where the emulator processes audio data streams between the guest operating system and the host system, making it particularly dangerous in environments where virtualization is extensively utilized.
The technical root cause of this vulnerability stems from inadequate memory deallocation practices within the audio capture loop of the QEMU emulator. When audio capture is initiated and subsequently terminated multiple times, the system fails to properly release allocated memory segments that were reserved for audio processing buffers and related data structures. This memory management failure creates a gradual degradation of system performance as the virtual machine continues to consume increasing amounts of physical memory without proper cleanup. The vulnerability is classified under CWE-401 as a weakness related to improper release of memory, and it directly impacts the availability and stability of the virtualization environment. The flaw operates at the kernel-level emulation layer where audio devices are emulated, making it particularly challenging to detect and remediate since it occurs within the core virtualization infrastructure rather than in user-space applications.
The operational impact of this vulnerability extends beyond simple resource exhaustion, creating a potential vector for sophisticated denial of service attacks that can compromise entire virtualization clusters. Remote attackers can exploit this weakness by repeatedly initiating audio capture sessions, causing progressive memory consumption that can eventually lead to system crashes or complete virtual machine shutdowns. This vulnerability is particularly concerning in cloud computing environments and data centers where multiple virtual machines share physical resources, as a single compromised guest operating system could gradually consume memory across the entire infrastructure. The attack requires minimal privileges and can be executed remotely, making it an attractive target for adversaries seeking to disrupt services without requiring elevated access rights. According to ATT&CK framework categorization, this vulnerability aligns with T1499.004 - Endpoint Denial of Service, and represents a classic example of resource exhaustion attacks that can be leveraged for broader system compromise.
Mitigation strategies for CVE-2017-8309 should focus on immediate patching of affected QEMU versions, as the vulnerability was resolved through proper memory deallocation implementation in subsequent releases. System administrators should implement monitoring solutions that track memory consumption patterns in virtualized environments to detect anomalous usage that may indicate exploitation attempts. Network segmentation and access control measures should be enhanced to limit the potential attack surface, particularly in environments where guest operating systems have elevated privileges. Additionally, virtual machine resource limits should be configured to prevent individual guests from consuming excessive memory resources, providing a safety net against memory leak exploitation. The vulnerability highlights the importance of thorough memory management testing in virtualization platforms and underscores the need for continuous security auditing of core emulator components that handle device emulation functions. Organizations should also consider implementing automated patch management systems to ensure rapid deployment of security updates across virtualization infrastructure, as this vulnerability demonstrates how seemingly minor memory management issues can have significant operational impacts on large-scale virtualized environments.