CVE-2018-12035 in YARA
Summary
by MITRE
In YARA 3.7.1 and prior, parsing a specially crafted compiled rule file can cause an out of bounds write vulnerability in yr_execute_code in libyara/exec.c.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability identified as CVE-2018-12035 represents a critical out-of-bounds write flaw within the YARA threat hunting and malware detection framework version 3.7.1 and earlier. This vulnerability resides in the libyara/exec.c component of the software, specifically within the yr_execute_code function that handles execution of compiled rule files. YARA is widely utilized by security professionals, incident responders, and organizations for identifying and classifying malware samples through pattern matching techniques. The flaw manifests when the software processes specially crafted compiled rule files that contain malformed data structures or unexpected control flow patterns.
The technical implementation of this vulnerability stems from inadequate bounds checking during the execution phase of compiled YARA rules. When the yr_execute_code function processes malicious input, it fails to properly validate array indices or memory access boundaries before writing data to memory locations. This allows an attacker to craft a compiled rule file that, when loaded and executed by YARA, triggers memory corruption through unauthorized write operations beyond the allocated buffer boundaries. The vulnerability is classified as a memory corruption issue that can potentially lead to arbitrary code execution or application crashes.
The operational impact of CVE-2018-12035 extends beyond simple application instability, as it represents a potential remote code execution vector that could be exploited in environments where YARA is used to process untrusted rule files. Security analysts and malware researchers who regularly work with YARA for threat hunting operations face significant risk, as adversaries could potentially embed malicious payloads within compiled rule files that would execute when processed by vulnerable YARA installations. This vulnerability directly affects the integrity of security workflows and could compromise the security posture of organizations relying on YARA for malware detection and analysis. The flaw aligns with CWE-787, which describes out-of-bounds write vulnerabilities, and represents a critical weakness in the software's memory management and input validation mechanisms.
Mitigation strategies for this vulnerability require immediate patching of YARA installations to version 3.8.0 or later, which includes fixes for the bounds checking issues in the execution engine. Organizations should also implement strict input validation policies for compiled rule files, particularly when processing external or untrusted sources. Security teams should consider isolating YARA execution environments and implementing sandboxing mechanisms to limit potential exploitation impact. The vulnerability demonstrates the importance of proper memory safety practices in security tools and aligns with ATT&CK technique T1059.007 for execution through scripting, as the flaw could enable attackers to execute arbitrary code through malicious rule file manipulation. Additionally, organizations should conduct comprehensive vulnerability assessments of their YARA usage patterns and implement monitoring for suspicious rule file processing activities.