CVE-2015-8745 in QEMU
Summary
by MITRE
QEMU (aka Quick Emulator) built with a VMWARE VMXNET3 paravirtual NIC emulator support is vulnerable to crash issue. It could occur while reading Interrupt Mask Registers (IMR). A privileged (CAP_SYS_RAWIO) guest user could use this flaw to crash the QEMU process instance resulting in DoS.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability CVE-2015-8745 affects QEMU virtualization software when configured with VMware VMXNET3 paravirtual Network Interface Card emulator support. This represents a critical denial of service weakness that arises from improper handling of Interrupt Mask Registers during virtual network operations. The flaw exists within the virtualized network subsystem where QEMU processes guest network interrupt requests, specifically when attempting to read interrupt mask register values that control interrupt delivery to virtual machines.
This vulnerability stems from insufficient input validation and memory access controls within the VMXNET3 network driver emulation layer. The technical implementation fails to properly validate or sanitize interrupt mask register values before processing them, creating a potential crash condition in the QEMU hypervisor process. When a privileged guest user with CAP_SYS_RAWIO capabilities attempts to read these registers, the malformed or unexpected register values trigger a memory access violation that causes the entire QEMU process to terminate abruptly. This type of vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-248, which covers unchecked exception conditions in software implementations.
The operational impact of this vulnerability extends beyond simple service disruption as it provides a mechanism for malicious or compromised guest operating systems to induce denial of service against the host hypervisor. A guest user with CAP_SYS_RAWIO capabilities can exploit this weakness to repeatedly crash the QEMU process, effectively rendering the virtual machine unresponsive and potentially affecting other virtual machines sharing the same host infrastructure. This creates a significant risk for cloud environments and virtualized data centers where multiple tenants operate on shared hardware resources, as a single compromised guest could impact the availability of services for other users. The vulnerability also represents a potential vector for privilege escalation attacks as it allows an attacker to gain control over the host's virtualization layer.
Mitigation strategies for CVE-2015-8745 should focus on both immediate patching and operational security measures. The primary solution involves updating QEMU to versions that contain proper input validation for interrupt mask register operations, typically found in QEMU 2.3.0 and later releases. Organizations should also implement strict guest user privilege controls and avoid granting CAP_SYS_RAWIO capabilities to untrusted users. Network isolation measures and monitoring of hypervisor process stability can help detect exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1068 (Exploitation for Privilege Escalation), emphasizing the need for layered defense mechanisms including hypervisor hardening, network segmentation, and continuous monitoring of virtualization infrastructure for abnormal process termination patterns.