CVE-2017-5931 in QEMU
Summary
by MITRE
Integer overflow in hw/virtio/virtio-crypto.c in QEMU (aka Quick Emulator) allows local guest OS privileged users to cause a denial of service (QEMU process crash) or possibly execute arbitrary code on the host via a crafted virtio-crypto request, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 11/22/2022
The vulnerability identified as CVE-2017-5931 represents a critical integer overflow flaw within the QEMU virtualization platform's virtio-crypto subsystem. This issue affects the hypervisor's ability to properly handle cryptographic operations when emulated within virtual machines, creating a pathway for malicious exploitation that can compromise both guest and host system integrity. The vulnerability resides in the hw/virtio/virtio-crypto.c file, which implements the virtio-crypto device emulation that allows virtual machines to perform cryptographic operations through the QEMU hypervisor.
The technical flaw manifests as an integer overflow condition that occurs during the processing of virtio-crypto requests from guest operating systems. When a privileged user within the guest environment submits a specially crafted cryptographic request, the integer overflow triggers a heap-based buffer overflow in the host QEMU process. This buffer overflow vulnerability stems from inadequate input validation and bounds checking within the cryptographic request handling code, allowing attackers to manipulate memory allocation sizes and subsequently overwrite adjacent memory regions. The vulnerability is classified as a CWE-190 - Integer Overflow or Wraparound, which is a well-documented weakness in software systems where integer arithmetic operations exceed the maximum representable value for the data type.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it presents a potential pathway for privilege escalation and arbitrary code execution on the host system. Local guest OS users with sufficient privileges can exploit this vulnerability to crash the QEMU process, effectively causing a denial of service that disrupts virtual machine operations. However, the more concerning aspect involves the potential for arbitrary code execution on the host, which would allow attackers to escape the virtual machine isolation boundaries and gain elevated privileges on the underlying physical host. This represents a significant compromise of the fundamental security model that virtualization platforms rely upon, as it breaks the isolation between guest and host environments. The attack vector requires a privileged user within the guest system, but the potential for escalation makes this vulnerability particularly dangerous in multi-tenant environments where different users share the same hypervisor infrastructure.
Mitigation strategies for CVE-2017-5931 should prioritize immediate patching of QEMU installations to address the integer overflow and buffer overflow conditions. System administrators should ensure that all virtualization environments are updated with the latest QEMU releases that contain fixes for this vulnerability. Additionally, implementing network segmentation and access controls to limit guest user privileges can reduce the attack surface, although this approach does not eliminate the vulnerability itself. The mitigation approach aligns with ATT&CK technique T1068 - Exploitation for Privilege Escalation, which focuses on using vulnerabilities to gain elevated privileges. Organizations should also consider implementing monitoring solutions that can detect anomalous behavior patterns associated with buffer overflow exploits, particularly in virtualization environments. The vulnerability demonstrates the importance of rigorous input validation and bounds checking in hypervisor code, as highlighted by CWE-129 - Improper Validation of Array Index, which is directly related to the buffer overflow conditions that occur in this vulnerability. Regular security assessments of virtualization platforms and maintaining up-to-date security patches remain essential practices for preventing exploitation of such critical vulnerabilities.