CVE-2022-20792 in ClamAV
Summary
by MITRE • 08/10/2022
A vulnerability in the regex module used by the signature database load module of Clam AntiVirus (ClamAV) versions 0.104.0 through 0.104.2 and LTS version 0.103.5 and prior versions could allow an authenticated, local attacker to crash ClamAV at database load time, and possibly gain code execution. The vulnerability is due to improper bounds checking that may result in a multi-byte heap buffer overwflow write. An attacker could exploit this vulnerability by placing a crafted CDB ClamAV signature database file in the ClamAV database directory. An exploit could allow the attacker to run code as the clamav user.
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Analysis
by VulDB Data Team • 08/10/2022
The vulnerability identified as CVE-2022-20792 represents a critical security flaw within the Clam AntiVirus software ecosystem, specifically affecting versions 0.104.0 through 0.104.2 and the LTS version 0.103.5 and prior releases. This issue resides within the regex module that handles signature database loading operations, creating a pathway for authenticated local attackers to compromise system integrity. The vulnerability stems from inadequate bounds checking mechanisms that fail to properly validate input data during the processing of CDB ClamAV signature database files, fundamentally undermining the software's defensive capabilities.
The technical implementation of this vulnerability manifests as a multi-byte heap buffer overflow condition that occurs during database load operations. When ClamAV processes a specially crafted CDB file, the regex module fails to enforce proper boundary limits on memory allocations, allowing malicious data to overwrite adjacent memory regions. This memory corruption scenario creates exploitable conditions that can lead to arbitrary code execution within the context of the clamav user account. The flaw operates at the intersection of software input validation and memory management, where insufficient bounds checking permits data to exceed allocated buffer boundaries and corrupt heap memory structures.
From an operational perspective, the impact of this vulnerability extends beyond simple system crashes to potentially enable full system compromise. An authenticated local attacker who can place malicious signature files in the ClamAV database directory gains the capability to execute arbitrary code with the privileges of the clamav user account. This presents a significant risk in environments where ClamAV operates with elevated privileges or where the clamav user has access to sensitive system resources. The vulnerability's exploitation requires local authentication but does not necessitate network access, making it particularly concerning for systems where local privilege escalation is a potential concern.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. From an adversarial perspective, this flaw maps to several ATT&CK techniques including privilege escalation through legitimate system tools and execution through valid accounts. The attack vector requires local system access and file placement capabilities, but once exploited, could provide attackers with persistent access through the clamav user context. Organizations should consider this vulnerability as part of broader security assessments that evaluate the attack surface of anti-virus and security tooling.
Mitigation strategies for CVE-2022-20792 should prioritize immediate patching of affected ClamAV versions to the latest releases that contain the necessary bounds checking fixes. System administrators should implement strict file access controls for the ClamAV database directory to prevent unauthorized modifications, while also monitoring for suspicious file placement activities. Additional protective measures include running ClamAV with minimal privileges, implementing file integrity monitoring solutions, and conducting regular security assessments of security tooling configurations. Organizations should also consider implementing network segmentation to limit the potential impact of any successful exploitation attempts and establish robust incident response procedures for detecting and responding to such vulnerabilities.