CVE-2003-0946 in ClamAV
Summary
by MITRE
Format string vulnerability in clamav-milter for Clam AntiVirus 0.60 through 0.60p, and other versions before 0.65, allows remote attackers to cause a denial of service and possibly execute arbitrary code via format string specifiers in the email address argument of a "MAIL FROM" command.
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Analysis
by VulDB Data Team • 06/15/2018
The vulnerability described in CVE-2003-0946 represents a critical format string vulnerability within the clamav-milter component of Clam AntiVirus software. This issue affects versions 0.60 through 0.60p and other releases prior to 0.65, creating a significant security risk for email servers that rely on this anti-virus filtering mechanism. The flaw specifically manifests when processing email address arguments within the "MAIL FROM" command of the Simple Mail Transfer Protocol, where improper input validation allows malicious actors to inject format string specifiers that can be exploited for arbitrary code execution or denial of service conditions.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters during the SMTP mail transaction process. When the clamav-milter component processes the email address argument in the MAIL FROM command, it fails to properly sanitize or validate the input before using it in format string operations. This allows attackers to inject format specifiers such as %n, %s, or %x that can cause the application to read from or write to arbitrary memory locations. The vulnerability stems from the improper handling of user-supplied data in printf-style functions, which is a well-documented weakness classified under CWE-134 in the Common Weakness Enumeration catalog. This particular weakness is categorized as a format string vulnerability that can lead to information disclosure, application crashes, or potentially full system compromise depending on the execution environment and memory layout.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution within the context of the mail server process. Attackers can leverage this flaw to execute arbitrary commands on the affected system, especially when the mail server process runs with elevated privileges. The vulnerability affects email infrastructure components that utilize clamav-milter for real-time virus scanning, making it particularly dangerous for organizations that depend on email security services. The attack surface is broad as any system running the vulnerable version of clamav-milter and processing SMTP traffic is potentially exposed to exploitation. This vulnerability directly aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) as it enables attackers to execute commands through the exploitation of a format string vulnerability in a mail server component.
Mitigation strategies for this vulnerability require immediate patching of affected systems to versions 0.65 or later where the format string vulnerability has been addressed. Organizations should implement network segmentation to limit exposure of vulnerable mail servers to untrusted networks and consider disabling clamav-milter functionality until patches are applied. Additional protective measures include implementing strict input validation at network boundaries, monitoring for unusual SMTP traffic patterns, and applying the principle of least privilege to mail server processes to minimize potential damage from successful exploitation. Security teams should also conduct thorough vulnerability assessments to identify all systems running affected versions of Clam AntiVirus and establish monitoring procedures to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation and secure coding practices in network security applications, particularly those handling untrusted data from external sources. Organizations should maintain updated vulnerability management processes to ensure timely patch deployment and reduce the window of exposure to known vulnerabilities in their email infrastructure components.