CVE-2015-1345 in grep
Summary
by MITRE
The bmexec_trans function in kwset.c in grep 2.19 through 2.21 allows local users to cause a denial of service (out-of-bounds heap read and crash) via crafted input when using the -F option.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability identified as CVE-2015-1345 resides within the grep utility's kwset.c component, specifically in the bmexec_trans function that handles pattern matching operations. This flaw affects grep versions 2.19 through 2.21 and represents a critical security issue that can be exploited by local attackers to induce denial of service conditions. The vulnerability manifests when users employ the -F option, which enables fixed-string pattern matching, creating a scenario where malformed input can trigger unexpected behavior in the underlying pattern matching algorithm.
The technical root cause of this vulnerability stems from inadequate input validation within the bmexec_trans function, which processes pattern matching operations using the Boyer-Moore algorithm variant. When grep encounters crafted input through the -F flag, the function fails to properly bounds-check memory accesses, leading to an out-of-bounds heap read condition. This memory access violation occurs because the algorithm does not adequately validate array indices or buffer boundaries before accessing heap-allocated memory regions. The flaw falls under CWE-125, which describes out-of-bounds read conditions, and specifically manifests as a heap-based buffer overflow scenario that can result in program termination.
The operational impact of CVE-2015-1345 extends beyond simple denial of service, as it can be leveraged to crash processes that utilize grep for pattern matching operations. Attackers can craft malicious input strings that, when processed by grep with the -F option, cause the application to read memory locations outside its intended bounds. This can result in segmentation faults, application crashes, or potentially more severe consequences depending on the execution context. The vulnerability is particularly concerning in environments where grep is used as a system utility or in automated processes, as it can disrupt critical system operations and potentially provide a foothold for further exploitation attempts.
Mitigation strategies for this vulnerability include immediate patching of grep installations to versions 2.22 or later, where the issue has been resolved through proper bounds checking and input validation. System administrators should also implement input sanitization measures for any applications that process user-provided data through grep commands, particularly when using the -F option. Additionally, monitoring for unusual grep process behavior or crashes can help detect exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and denial of service, as it can be used to compromise system availability and potentially create opportunities for more sophisticated attacks. Organizations should also consider implementing application whitelisting policies that restrict execution of potentially vulnerable versions of grep, particularly in environments where untrusted input processing is common.