CVE-2017-18043 in QEMU
Summary
by MITRE
Integer overflow in the macro ROUND_UP (n, d) in Quick Emulator (Qemu) allows a user to cause a denial of service (Qemu process crash).
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability CVE-2017-18043 represents a critical integer overflow flaw within the Quick Emulator (QEMU) software that can be exploited to cause a denial of service condition. This issue specifically affects the ROUND_UP macro implementation which is commonly used for mathematical operations involving rounding up values to the nearest multiple of a given divisor. The vulnerability manifests when processing certain input parameters that cause the arithmetic operations within the macro to exceed the maximum representable value for the integer data type, leading to unexpected behavior and system instability.
The technical implementation of this vulnerability resides in the ROUND_UP macro definition where integer overflow occurs during the calculation process. When a user provides malicious input parameters to QEMU that trigger this macro, the arithmetic operation n + d - 1 performs an integer overflow, causing the result to wrap around to a negative value or zero. This overflow condition directly impacts the QEMU process execution, causing it to crash and terminate unexpectedly. The vulnerability is particularly concerning because it can be triggered through normal user interaction with the emulator, making it a significant threat to systems that rely on QEMU for virtualization operations.
From an operational impact perspective, this vulnerability severely undermines the reliability and availability of systems using QEMU as their virtualization platform. The denial of service condition affects not only the immediate QEMU process but can also impact the overall stability of virtualized environments where multiple guests or processes depend on the emulator's functionality. Attackers can exploit this vulnerability to disrupt services, cause system downtime, and potentially create conditions that may be leveraged for more sophisticated attacks. The vulnerability affects various QEMU versions and can be exploited across different operating systems and hardware configurations where QEMU is deployed.
The vulnerability maps directly to CWE-191, which describes integer underflow (wrap under) and integer overflow (wrap over) conditions that can lead to unpredictable behavior and system crashes. Additionally, this issue aligns with ATT&CK technique T1499.004 which covers network denial of service attacks through resource exhaustion or process termination. The exploitation of this vulnerability requires minimal privileges and can be accomplished through carefully crafted input parameters that cause the integer overflow condition. Organizations using QEMU should prioritize immediate patching and implementation of input validation measures to prevent exploitation of this vulnerability.
Mitigation strategies should focus on applying the official security patches released by the QEMU development team, which typically involve correcting the integer overflow by implementing proper bounds checking or using larger integer data types. System administrators should also implement monitoring solutions to detect unusual process termination patterns that may indicate exploitation attempts. Additional defensive measures include restricting user privileges when running QEMU processes, implementing input sanitization for all parameters processed by the emulator, and maintaining up-to-date security information through vulnerability management programs. Regular security assessments and code reviews focusing on integer arithmetic operations can help identify similar vulnerabilities in other components of virtualization software stacks.