CVE-2017-15268 in QEMU
Summary
by MITRE
Qemu through 2.10.0 allows remote attackers to cause a memory leak by triggering slow data-channel read operations, related to io/channel-websock.c.
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Analysis
by VulDB Data Team • 01/03/2023
The vulnerability identified as CVE-2017-15268 affects QEMU versions through 2.10.0 and represents a memory leak issue that can be exploited by remote attackers to cause system instability. This flaw exists within the web socket data channel implementation in QEMU's io/channel-websock.c component, which is responsible for handling WebSocket connections for virtual machine communication. The vulnerability arises from insufficient memory management during slow data-channel read operations, creating conditions where allocated memory is not properly released back to the system.
The technical flaw manifests when remote attackers can manipulate the data channel read operations to trigger a gradual accumulation of memory usage within the QEMU process. This occurs because the WebSocket implementation fails to properly handle resource cleanup during extended or slow read operations, leading to memory fragments that remain allocated even after the data transfer completes. The vulnerability is particularly concerning because it allows for a gradual degradation of system performance that can eventually lead to system crashes or denial of service conditions. The memory leak is specifically tied to the WebSocket protocol handling within QEMU's virtualization framework, making it applicable to any virtual environment that utilizes WebSocket connections for communication between the host and guest operating systems.
From an operational impact perspective, this vulnerability enables remote attackers to consume system resources progressively over time, potentially leading to complete system exhaustion of available memory. The slow data-channel read operations can be triggered through crafted WebSocket connections, making this attack vector accessible to anyone with network access to the QEMU instance. In virtualized environments, this memory leak can affect not only the individual QEMU process but also the overall host system performance, as memory exhaustion can cause the hypervisor to become unresponsive or force the termination of other virtual machines running on the same host. The vulnerability is particularly dangerous in cloud computing environments where multiple virtual machines share the same physical host resources, as a single compromised QEMU instance could impact the entire hosting infrastructure.
Mitigation strategies for CVE-2017-15268 should prioritize immediate patching of QEMU instances to versions 2.10.1 or later where the memory leak has been addressed through proper resource cleanup mechanisms. Organizations should also implement network segmentation and access controls to limit exposure of QEMU instances to untrusted networks, reducing the attack surface for remote exploitation. Monitoring systems should be deployed to track memory usage patterns of QEMU processes, enabling early detection of potential memory leak activity. Additionally, implementing resource limits and quotas for virtual machine processes can help contain the impact of such vulnerabilities by preventing a single instance from consuming excessive system resources. This vulnerability aligns with CWE-401, which addresses improper handling of memory allocation failures, and represents a classic example of how protocol implementation flaws can lead to resource exhaustion attacks that fall under ATT&CK technique T1499 for resource exhaustion. Regular security assessments of virtualization environments should include verification of QEMU component versions and proper memory management practices to prevent similar issues from occurring in other components of the virtualization stack.