CVE-2009-1371 in ClamAV
Summary
by MITRE
The CLI_ISCONTAINED macro in libclamav/others.h in ClamAV before 0.95.1 allows remote attackers to cause a denial of service (application crash) via a malformed file with UPack encoding.
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2009-1371 represents a critical denial of service flaw within the ClamAV antivirus software ecosystem. This issue affects versions prior to 0.95.1 and specifically targets the CLI_ISCONTAINED macro implementation within the libclamav/others.h file. The vulnerability manifests when ClamAV processes malformed files that employ UPack encoding, creating a scenario where legitimate security software becomes compromised through crafted malicious inputs.
The technical root cause of this vulnerability lies in the improper handling of boundary checks within the CLI_ISCONTAINED macro during file processing operations. When ClamAV encounters a file with malformed UPack encoding, the macro fails to properly validate input parameters, leading to memory access violations and subsequent application crashes. This flaw operates at the core of ClamAV's file analysis engine, where the macro's inadequate boundary validation creates a condition where arbitrary memory locations can be accessed or manipulated, ultimately resulting in a complete application termination.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides remote attackers with a method to compromise the availability of antivirus services. In enterprise environments where ClamAV serves as a critical security component for malware detection and prevention, such a vulnerability could be exploited to create widespread service outages. Attackers can craft specific UPack-encoded files that trigger the macro's failure conditions, causing the antivirus daemon to crash repeatedly and potentially leading to system instability or complete service unavailability. This represents a significant threat to network security infrastructure where ClamAV is deployed as a primary defense mechanism.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and demonstrates characteristics consistent with improper input validation patterns that can lead to memory corruption issues. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service, where adversaries leverage software flaws to disrupt services. The exploitability of this vulnerability requires minimal sophistication and can be executed remotely, making it particularly dangerous in environments where ClamAV processes files from untrusted sources such as email attachments, web downloads, or file sharing systems.
Mitigation strategies for this vulnerability include immediate upgrading to ClamAV version 0.95.1 or later, which contains the necessary patches to address the boundary checking issues within the CLI_ISCONTAINED macro. Organizations should also implement additional defensive measures such as file type validation, content scanning with multiple antivirus solutions, and network segmentation to limit the potential impact of such attacks. Security administrators should monitor for exploitation attempts and maintain updated threat intelligence feeds to identify malicious files that may leverage this vulnerability. The patch addresses the underlying memory access violation by implementing proper boundary checks and input validation within the affected macro, ensuring that all file processing operations maintain memory safety and prevent unauthorized access patterns that could lead to application crashes or system instability.