CVE-2008-6680 in ClamAV
Summary
by MITRE
libclamav/pe.c in ClamAV before 0.95 allows remote attackers to cause a denial of service (crash) via a crafted EXE file that triggers a divide-by-zero error.
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2008-6680 resides within the ClamAV antivirus software's libclamav library, specifically in the pe.c module responsible for processing Portable Executable files. This flaw represents a classic divide-by-zero error that occurs when the software encounters a specially crafted executable file during malware scanning operations. The vulnerability affects ClamAV versions prior to 0.95, making it a significant concern for organizations relying on older antivirus implementations. The issue stems from inadequate input validation within the PE file parsing logic where the software fails to properly handle malformed executable structures that contain zero values in critical calculation contexts.
The technical exploitation of this vulnerability occurs when ClamAV attempts to parse a maliciously constructed PE file that contains malformed headers or section data. During the processing of such files, the software's code executes a division operation where the divisor is unexpectedly set to zero, causing an immediate crash of the antivirus daemon. This divide-by-zero condition triggers a segmentation fault or similar system-level exception that terminates the scanning process, effectively rendering the antivirus service unavailable for subsequent scanning operations. The flaw demonstrates poor error handling practices and insufficient bounds checking within the PE file parser component, which is a common pattern seen in buffer overflow and arithmetic error vulnerabilities.
From an operational perspective, this vulnerability creates a remote denial of service condition that can be exploited by attackers without requiring authentication or privileged access. An attacker can simply craft a malicious executable file and deliver it to a system running vulnerable ClamAV software, causing the antivirus service to crash and potentially leading to extended downtime for the affected system. The impact extends beyond simple service disruption as it can result in complete antivirus protection failure during critical scanning operations, leaving systems vulnerable to actual malware infections while the service is offline. Organizations may experience cascading effects as the antivirus daemon restarts, potentially causing scanning delays and gaps in protection coverage.
The vulnerability aligns with CWE-369, which specifically addresses the divide-by-zero error condition that occurs when a program attempts to divide by zero. This weakness is classified as a software fault that can lead to system instability and denial of service conditions. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain where adversaries first establish a foothold and then use denial of service techniques to disrupt security monitoring capabilities. The attack surface is particularly concerning in enterprise environments where ClamAV is deployed as a central security service, as a single compromised file could potentially disrupt security operations across multiple systems.
Mitigation strategies for CVE-2008-6680 primarily involve immediate patching of ClamAV installations to version 0.95 or later, which contains the necessary fixes for proper error handling and input validation. Organizations should also implement network-level controls to prevent execution of suspicious executable files and maintain robust backup and recovery procedures for antivirus services. Additional defensive measures include monitoring for unusual daemon crashes and implementing redundant antivirus solutions to maintain protection coverage during patching windows. System administrators should also consider implementing file reputation services and behavioral analysis tools to detect and block potentially malicious files before they can trigger the vulnerability within the antivirus engine.