CVE-2004-1876 in ClamAV
Summary
by MITRE
The "%f" feature in the VirusEvent directive in Clam AntiVirus daemon (clamd) before 0.70 allows local users to execute arbitrary commands via shell metacharacters in a file name.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability identified as CVE-2004-1876 represents a critical command injection flaw within the Clam AntiVirus daemon implementation. This issue specifically affects the VirusEvent directive functionality where the "%f" feature is designed to pass file names to external commands for processing. The flaw arises from insufficient input validation and sanitization within the clamd daemon's handling of file names that contain shell metacharacters. When a malicious user places a file with specially crafted shell metacharacters in its name, the daemon processes this input without proper escaping or filtering, creating a dangerous execution path.
The technical exploitation of this vulnerability occurs through the improper handling of file names within the VirusEvent directive configuration. The "%f" parameter substitution mechanism fails to sanitize user-supplied file names before incorporating them into shell command executions. This design flaw enables local attackers to inject arbitrary shell commands that get executed with the privileges of the clamd daemon process. The vulnerability is particularly concerning because it operates at the daemon level, meaning successful exploitation could allow attackers to execute commands with elevated privileges typically associated with anti-virus system processes. This represents a classic command injection vulnerability that falls under CWE-78, which specifically addresses improper neutralization of special elements used in OS commands.
From an operational perspective, this vulnerability creates significant security implications for systems running affected versions of Clam AntiVirus. Local users who can place files in directories monitored by clamd can leverage this weakness to execute arbitrary code on the system. The attack vector is particularly dangerous because it requires minimal privileges beyond the ability to create files in monitored directories. The impact extends beyond simple command execution to potentially allow full system compromise, as the clamd daemon typically runs with elevated permissions to perform anti-virus operations. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically targeting local command execution through shell injection mechanisms.
The remediation for CVE-2004-1876 requires immediate patching of Clam AntiVirus daemon to version 0.70 or later, which implements proper input sanitization for the VirusEvent directive. System administrators should also review all VirusEvent directive configurations to ensure that file name handling is properly escaped and validated before command execution. Additional mitigations include implementing proper file name validation at the application level, restricting write permissions to directories monitored by clamd, and employing privilege separation techniques to limit the impact of potential exploitation. Organizations should also consider implementing network segmentation and monitoring to detect unusual command execution patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation in security-critical systems and highlights the need for comprehensive security testing of all command execution pathways within anti-virus and security software implementations.