CVE-2017-9465 in YARA
Summary
by MITRE
The yr_arena_write_data function in YARA 3.6.1 allows remote attackers to cause a denial of service (buffer over-read and application crash) or obtain sensitive information from process memory via a crafted file that is mishandled in the yr_re_fast_exec function in libyara/re.c and the _yr_scan_match_callback function in libyara/scan.c.
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Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2017-9465 represents a critical buffer over-read flaw within the YARA threat hunting and malware detection framework version 3.6.1. This issue stems from improper memory handling in the yr_arena_write_data function which processes crafted input files that subsequently trigger malformed execution paths within the YARA library. The vulnerability manifests when YARA attempts to process maliciously constructed files through the yr_re_fast_exec function located in libyara/re.c and the _yr_scan_match_callback function in libyara/scan.c. These functions fail to properly validate input boundaries during pattern matching operations, creating exploitable conditions that can be leveraged by remote attackers to manipulate memory access patterns beyond allocated buffer limits.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in software implementations. The flaw operates through a classic buffer over-read scenario where the yr_re_fast_exec function processes regular expression patterns without adequate boundary checking, allowing an attacker to craft input that causes the application to read memory locations beyond intended buffer limits. This over-read behavior can result in two distinct attack vectors: denial of service through application crashes or information disclosure where sensitive process memory contents become accessible to attackers. The vulnerability's exploitation pathway demonstrates the dangerous intersection of regular expression engine implementation and memory management, where pattern matching operations can be manipulated to access arbitrary memory locations.
From an operational impact perspective, this vulnerability presents significant risks to organizations relying on YARA for security operations and threat hunting activities. The remote attack vector means that adversaries can potentially compromise systems without requiring local access, making this particularly dangerous in environments where YARA is used for automated file analysis or integrated into security monitoring systems. The potential for information disclosure creates additional risks where attackers might extract sensitive data from process memory, including cryptographic keys, authentication tokens, or other confidential information. Organizations using YARA for malware analysis, network traffic inspection, or security automation frameworks face elevated risk exposure when systems are vulnerable to this specific memory handling flaw.
The attack surface for this vulnerability extends across multiple security domains including incident response, malware analysis, and automated security monitoring systems. Security teams utilizing YARA for threat hunting operations may experience service interruptions when processing malicious files, potentially disrupting critical security workflows and forensic analysis capabilities. The vulnerability's classification under the ATT&CK framework would fall within the T1059.007 technique for command and scripting interpreter, as the denial of service aspect could be leveraged to disrupt security tooling. Mitigation strategies should prioritize immediate patching of affected YARA versions, implementation of input validation controls, and deployment of network-based intrusion detection rules that can identify and block malicious file patterns targeting this specific buffer over-read condition. Organizations should also consider implementing sandboxing mechanisms and strict file validation procedures to prevent exploitation of this memory corruption vulnerability in production environments.