CVE-2018-11237 in C Library
Summary
by MITRE
An AVX-512-optimized implementation of the mempcpy function in the GNU C Library (aka glibc or libc6) 2.27 and earlier may write data beyond the target buffer, leading to a buffer overflow in __mempcpy_avx512_no_vzeroupper.
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Analysis
by VulDB Data Team • 03/14/2023
The vulnerability CVE-2018-11237 represents a critical buffer overflow flaw in the GNU C Library implementation of the mempcpy function. This issue specifically affects glibc versions 2.27 and earlier, where an optimized AVX-512 implementation introduces a memory corruption vulnerability that can be exploited by malicious actors. The flaw manifests in the __mempcpy_avx512_no_vzeroupper function which is designed to leverage advanced vector extensions for improved performance but inadvertently creates a condition where data can be written beyond the intended buffer boundaries.
The technical root cause of this vulnerability lies in the improper handling of memory operations within the AVX-512 optimized code path. When the mempcpy function processes data using AVX-512 instructions, the implementation fails to properly account for the full extent of memory operations required for the vectorized execution. This results in a classic buffer overflow condition where the processor writes data beyond the allocated memory region, potentially overwriting adjacent memory locations. The vulnerability is particularly dangerous because it occurs in a fundamental system library function that is widely used across numerous applications and system components. According to CWE-121, this represents a stack-based buffer overflow, while the underlying issue aligns with CWE-787 which describes out-of-bounds write vulnerabilities.
The operational impact of CVE-2018-11237 extends far beyond individual application crashes, as it affects the core system libraries that underpin countless software applications. When exploited, this vulnerability can lead to arbitrary code execution, denial of service conditions, or information disclosure across the entire system. Attackers can leverage this flaw to bypass security mechanisms such as stack canaries, address space layout randomization, and other memory protection features. The vulnerability is particularly concerning in server environments where glibc is used by multiple services and applications, potentially allowing attackers to gain elevated privileges or compromise entire systems. This aligns with ATT&CK technique T1055 which covers process injection and memory manipulation techniques that attackers might employ to exploit such buffer overflow conditions.
Mitigation strategies for CVE-2018-11237 primarily involve upgrading to patched versions of glibc where the AVX-512 optimization has been corrected or disabled. System administrators should prioritize updating their glibc installations to versions 2.28 or later where this vulnerability has been resolved. Additionally, organizations should consider implementing immediate workarounds such as disabling AVX-512 instruction set usage in applications or employing runtime protections like stack canaries and memory protection mechanisms. The vulnerability demonstrates the importance of thorough testing of optimized code paths in system libraries and highlights the risks associated with advanced instruction set optimizations that may introduce subtle security flaws. Security teams should monitor for exploitation attempts and implement network-based detection measures that can identify potential exploitation attempts targeting this specific vulnerability.