CVE-2015-5745 in QEMU
Summary
by MITRE
Buffer overflow in the send_control_msg function in hw/char/virtio-serial-bus.c in QEMU before 2.4.0 allows guest users to cause a denial of service (QEMU process crash) via a crafted virtio control message.
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Analysis
by VulDB Data Team • 10/01/2024
The vulnerability identified as CVE-2015-5745 represents a critical buffer overflow condition within the QEMU virtualization platform that specifically affects the virtio-serial-bus implementation. This flaw exists in the send_control_msg function located in the hw/char/virtio-serial-bus.c source file and impacts QEMU versions prior to 2.4.0. The vulnerability arises from insufficient input validation and bounds checking when processing virtio control messages, creating a scenario where maliciously crafted input can overwrite adjacent memory regions. The affected component operates within the virtual serial bus subsystem that facilitates communication between guest operating systems and host devices through virtio interfaces. This particular implementation flaw demonstrates a classic buffer overflow vulnerability that falls under CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it provides attackers with the capability to crash the QEMU process entirely, effectively terminating virtual machine operations and potentially disrupting service availability. Attackers exploiting this vulnerability can craft specially formatted virtio control messages that, when processed by the vulnerable send_control_msg function, trigger memory corruption that leads to process termination. The nature of this vulnerability means that any guest user with access to the virtual serial bus interface can potentially exploit this condition, making it particularly concerning in multi-tenant virtualization environments where guest isolation is critical. The attack vector requires minimal privileges within the guest operating system, as the vulnerability exists in the hypervisor's handling of guest-generated control messages rather than requiring direct system-level access. This characteristic aligns with ATT&CK technique T1059.001, which describes the use of command and scripting interpreters for execution, though in this case the exploitation occurs at the hypervisor level through crafted control messages.
Mitigation strategies for CVE-2015-5745 primarily focus on upgrading QEMU to version 2.4.0 or later, where the buffer overflow has been addressed through proper bounds checking and input validation mechanisms. System administrators should implement immediate patch management protocols to ensure all virtualization environments are updated with the latest QEMU releases that contain the necessary security fixes. Additionally, monitoring and logging should be enhanced to detect anomalous virtio control message patterns that might indicate exploitation attempts. Network segmentation and guest isolation measures can provide additional defense-in-depth layers, though they cannot fully compensate for the underlying vulnerability. The fix implemented in QEMU 2.4.0 demonstrates proper defensive programming practices that include input length validation, buffer size checks, and proper memory management techniques that prevent the overflow condition from occurring. Organizations should also consider implementing virtual machine introspection tools that can monitor for memory corruption patterns and provide early detection capabilities for similar vulnerabilities that may exist in other components of the virtualization stack. This vulnerability serves as a reminder of the critical importance of proper input validation in hypervisor components, as these systems often operate with elevated privileges and represent prime targets for exploitation attempts.