CVE-2017-2615 in Xen
Summary
by MITRE
Quick emulator (QEMU) built with the Cirrus CLGD 54xx VGA emulator support is vulnerable to an out-of-bounds access issue. It could occur while copying VGA data via bitblt copy in backward mode. A privileged user inside a guest could use this flaw to crash the QEMU process resulting in DoS or potentially execute arbitrary code on the host with privileges of QEMU process on the host.
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Analysis
by VulDB Data Team • 11/14/2022
The vulnerability identified as CVE-2017-2615 resides within the Quick Emulator QEMU implementation, specifically when utilizing the Cirrus CLGD 54xx VGA emulator support. This flaw manifests as an out-of-bounds memory access condition that occurs during VGA data copying operations through bitblt copy functionality operating in backward mode. The vulnerability represents a critical security issue that demonstrates how virtualization components can introduce severe risks when handling graphics operations within emulated environments.
The technical implementation of this vulnerability stems from insufficient bounds checking during graphics memory operations within the VGA emulator subsystem. When QEMU processes VGA data transfers using the bitblt copy function in backward mode, the emulator fails to properly validate memory access boundaries, allowing for memory access beyond allocated buffer limits. This particular flaw is categorized under CWE-129 Input Validation and CWE-787 Out-of-bounds Write, representing a classic buffer overflow condition that can be exploited through improper memory management during graphics operations. The vulnerability specifically affects the Cirrus Logic CLGD 54xx VGA controller implementation within QEMU's graphics subsystem.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable privilege escalation attacks. A malicious user with access to a guest operating system can leverage this flaw to crash the QEMU process, causing a denial of service condition that disrupts virtual machine operations. More critically, the vulnerability could allow for arbitrary code execution on the host system with the privileges of the QEMU process itself, effectively providing attackers with elevated access to the underlying host infrastructure. This represents a significant concern for cloud environments and multi-tenant virtualization platforms where guest isolation is paramount.
Mitigation strategies for CVE-2017-2615 should prioritize immediate patch application from QEMU maintainers, as the vulnerability affects core virtualization functionality. System administrators should implement network segmentation and access controls to limit guest user privileges, reducing the attack surface available to potential exploiters. The use of hypervisor-level security controls and monitoring for anomalous process behavior can help detect exploitation attempts. Additionally, organizations should consider disabling unnecessary graphics features within virtual machines when not required, as this reduces the attack surface and potential exploitation vectors. This vulnerability aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, highlighting the need for comprehensive security monitoring and patch management procedures across virtualization environments.