CVE-2007-4560 in ClamAV
Summary
by MITRE
clamav-milter in ClamAV before 0.91.2, when run in black hole mode, allows remote attackers to execute arbitrary commands via shell metacharacters that are used in a certain popen call, involving the "recipient field of sendmail."
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Analysis
by VulDB Data Team • 06/01/2025
The vulnerability identified as CVE-2007-4560 represents a critical command injection flaw in the clamav-milter component of ClamAV email filtering software. This issue affects versions prior to 0.91.2 and specifically manifests when the milter operates in black hole mode, a configuration where malicious email content is automatically discarded without notification to senders. The vulnerability stems from improper input validation within a popen system call that processes the recipient field of sendmail messages, creating an avenue for remote code execution through shell metacharacters.
The technical exploitation occurs when an attacker crafts malicious email messages containing shell metacharacters in the recipient field, which are then processed by the vulnerable clamav-milter service. The popen function, which executes shell commands, fails to properly sanitize the input from the sendmail recipient field, allowing attackers to inject arbitrary shell commands that execute with the privileges of the clamav-milter process. This represents a classic command injection vulnerability that can be classified under CWE-78, which specifically addresses improper neutralization of special elements used in OS commands.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with a persistent foothold within email infrastructure environments. Since clamav-milter typically runs with elevated privileges to properly filter email content, successful exploitation could lead to complete system compromise. Attackers could leverage this vulnerability to install backdoors, exfiltrate data, or establish persistent access to email servers, making it particularly dangerous in enterprise environments where email filtering is critical for security. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: Unix Shell, demonstrating how attackers can exploit poorly sanitized input to gain unauthorized system access.
Organizations running vulnerable versions of ClamAV should immediately implement mitigations including upgrading to version 0.91.2 or later, which contains the necessary patches to address the input validation issues. Network segmentation and access controls should be strengthened around email filtering infrastructure to limit potential attack vectors. Additionally, implementing proper input sanitization measures and monitoring for unusual command execution patterns can help detect exploitation attempts. The vulnerability highlights the importance of proper input validation in security-critical components and serves as a reminder that even email filtering systems can contain dangerous command injection flaws when not properly secured against malicious input.