CVE-2018-12034 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 read 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-2018-12034 represents a critical out-of-bounds read flaw within the YARA threat intelligence platform version 3.7.1 and earlier. This issue resides in the libyara/exec.c component where the yr_execute_code function processes compiled rule files, creating a potential avenue for remote code execution or denial of service attacks. The vulnerability specifically manifests when the software parses malformed compiled rule files that contain crafted data structures designed to trigger memory access violations beyond the allocated buffer boundaries. This type of vulnerability falls under the CWE-125 weakness category, which encompasses out-of-bounds read conditions that can lead to information disclosure, system instability, or arbitrary code execution. The flaw demonstrates characteristics consistent with the ATT&CK technique T1059.007 for command and scripting interpreter, as attackers could potentially leverage this vulnerability to execute malicious code within the context of the YARA processing environment.
The technical exploitation of this vulnerability requires an attacker to construct a specially crafted compiled rule file that, when processed by YARA, causes the yr_execute_code function to access memory locations beyond the intended buffer limits. This out-of-bounds read occurs during the execution phase of compiled rules, where the parser fails to properly validate the structure and size of the input data before attempting to access specific memory offsets. The vulnerability's impact extends beyond simple memory corruption as it can potentially expose sensitive information from adjacent memory regions, provide attackers with insights into memory layout, and in some cases enable further exploitation vectors. The flaw demonstrates a classic buffer over-read condition where the software assumes certain memory structures maintain expected boundaries without proper validation checks. This issue is particularly concerning in environments where YARA is used for malware analysis and threat hunting, as attackers could craft malicious rule files to compromise analysis systems.
The operational impact of CVE-2018-12034 extends across multiple security domains where YARA is deployed for automated threat detection and incident response. Organizations utilizing YARA for network monitoring, endpoint detection and response systems, or security information and event management platforms face significant risk when running vulnerable versions of the software. The vulnerability can be exploited through various attack vectors including email attachments, malicious files processed by security tools, or compromised rule repositories that attackers might inject into legitimate YARA workflows. This flaw particularly affects security operations centers that rely on automated rule processing, as a single compromised rule file could cause system crashes or enable remote code execution against the analysis infrastructure. The vulnerability's exploitation potential aligns with ATT&CK technique T1499 for endpoint denial of service, where attackers could disrupt security operations through targeted rule file manipulation, and T1068 for exploit for privilege escalation, where memory corruption could potentially be leveraged to gain elevated privileges.
Mitigation strategies for CVE-2018-12034 focus primarily on immediate version upgrades to YARA 3.8.0 or later, which includes patches specifically addressing the out-of-bounds read condition in the yr_execute_code function. Organizations should implement strict rule file validation procedures, including digital signature verification and automated scanning for malformed rule structures before deployment. Network segmentation and access controls should be enforced to limit the exposure of YARA processing systems to untrusted rule sources, while regular security assessments should verify that rule repositories remain free from malicious content. System administrators should also implement monitoring solutions that can detect anomalous rule processing patterns or memory access violations that might indicate exploitation attempts. Additionally, organizations should establish secure development practices for rule creation and distribution, ensuring that rule files undergo rigorous testing and validation before being integrated into production security environments. The vulnerability highlights the importance of input validation and memory safety practices in security software, particularly in components responsible for processing untrusted data from external sources, and underscores the necessity of maintaining up-to-date security tooling to protect against known vulnerabilities.