CVE-2017-6952 in Capstone
Summary
by MITRE
Integer overflow in the cs_winkernel_malloc function in winkernel_mm.c in Capstone 3.0.4 and earlier allows attackers to cause a denial of service (heap-based buffer overflow in a kernel driver) or possibly have unspecified other impact via a large value.
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Analysis
by VulDB Data Team • 03/17/2017
The vulnerability identified as CVE-2017-6952 represents a critical integer overflow flaw within the Capstone disassembly framework version 3.0.4 and earlier. This issue resides in the cs_winkernel_malloc function located in the winkernel_mm.c source file, which is specifically designed to handle memory allocation within kernel-mode drivers. The flaw occurs when the function processes large input values that exceed the capacity of the integer data type used for size calculations, leading to unexpected behavior in the memory management subsystem. This vulnerability is particularly concerning because it affects kernel-level components that are essential for system stability and security.
The technical implementation of this vulnerability stems from improper handling of integer arithmetic within the memory allocation routine. When an attacker supplies a large value that causes integer overflow during size calculation, the resulting corrupted memory allocation can lead to heap-based buffer overflow conditions. This occurs because the system attempts to allocate memory blocks of invalid sizes, potentially causing memory corruption that affects the kernel driver's operation. The overflow can manifest in multiple ways including memory overwrite conditions, allocation failures, or unpredictable behavior in the kernel space memory management. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, which is a well-documented weakness in software systems where integer arithmetic produces results that exceed the maximum value representable by the data type.
From an operational perspective, this vulnerability presents significant risks to system stability and security integrity. The heap-based buffer overflow can result in denial of service conditions where the kernel driver becomes unstable and crashes, potentially leading to system-wide outages. Additionally, the unspecified other impacts mentioned in the vulnerability description suggest that attackers might exploit this flaw for more sophisticated attacks beyond simple service disruption. The kernel driver environment provides elevated privileges, making this vulnerability particularly dangerous as it could potentially enable privilege escalation or other malicious activities. Attackers could leverage this vulnerability to compromise system integrity and availability, especially in environments where Capstone is used for kernel-level analysis or security monitoring.
Mitigation strategies for CVE-2017-6952 should prioritize immediate software updates to Capstone version 3.0.5 or later, which contains the necessary patches to address the integer overflow condition. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected versions of Capstone, particularly those utilizing kernel drivers or memory management components. Network segmentation and access controls should be implemented to limit exposure of systems that might be vulnerable. The remediation process should include thorough testing of updated software versions to ensure compatibility with existing applications and security tools that depend on Capstone functionality. Additionally, monitoring systems should be configured to detect unusual memory allocation patterns or driver behavior that might indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1059 for system execution and T1489 for input validation, emphasizing the need for robust memory management practices and proper integer overflow protection in kernel-level software components.