CVE-2016-10211 in YARA
Summary
by MITRE
libyara/grammar.y in YARA 3.5.0 allows remote attackers to cause a denial of service (use-after-free and application crash) via a crafted rule that is mishandled in the yr_parser_lookup_loop_variable function.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/24/2022
The vulnerability identified as CVE-2016-10211 represents a critical use-after-free condition within the YARA threat detection engine version 3.5.0. This flaw exists in the parser component located at libyara/grammar.y and specifically affects how the yr_parser_lookup_loop_variable function processes crafted rule inputs. The vulnerability stems from improper memory management during the parsing of YARA rules, where the application fails to properly handle memory references after they have been freed, creating a scenario where subsequent operations attempt to access already deallocated memory regions.
The technical exploitation of this vulnerability occurs when remote attackers submit maliciously crafted YARA rules that trigger the yr_parser_lookup_loop_variable function with malformed input parameters. During parsing, the parser allocates memory for loop variables and subsequently frees this memory, but fails to properly invalidate references to these freed memory locations. When the parser later attempts to access these freed variables during rule evaluation or compilation, it results in undefined behavior that manifests as application crashes or complete denial of service conditions. This type of vulnerability falls under CWE-416, which specifically addresses use-after-free conditions, and represents a classic example of memory safety issues in parsing engines.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged by attackers to potentially execute arbitrary code or cause system instability within environments that utilize YARA for threat detection and malware analysis. Organizations deploying YARA-based solutions for security monitoring, incident response, and malware detection are particularly at risk, as attackers could exploit this vulnerability to disrupt security operations or gain unauthorized access to systems. The vulnerability affects the core parsing functionality of YARA, which is widely used across security tools, malware analysis frameworks, and endpoint protection solutions, making it a critical concern for cybersecurity professionals managing threat detection infrastructure.
Mitigation strategies for CVE-2016-10211 should prioritize immediate patching of affected YARA versions to 3.6.0 or later, which contains the necessary memory management fixes. Organizations should also implement strict input validation for YARA rule files, particularly when processing rules from untrusted sources, and consider deploying sandboxed environments for rule evaluation. Network security teams should monitor for potential exploitation attempts and implement intrusion detection systems that can identify malicious rule patterns. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, as attackers could potentially use it to disrupt security monitoring capabilities. Additionally, organizations should conduct thorough testing of patched environments to ensure that the memory management fixes do not introduce regressions in legitimate rule processing functionality.