CVE-2008-1100 in ClamAV
Summary
by MITRE
Buffer overflow in the cli_scanpe function in libclamav (libclamav/pe.c) for ClamAV 0.92 and 0.92.1 allows remote attackers to execute arbitrary code via a crafted Upack PE file.
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Analysis
by VulDB Data Team • 04/07/2025
The vulnerability identified as CVE-2008-1100 represents a critical buffer overflow flaw within the ClamAV antivirus engine's libclamav library, specifically affecting versions 0.92 and 0.92.1. This issue resides in the cli_scanpe function located in the pe.c file, which processes Portable Executable files commonly used in windows operating systems. The vulnerability stems from inadequate input validation when handling crafted Upack PE files, which are compressed executable formats that can be used to obfuscate malicious code. The buffer overflow occurs when the scanning engine attempts to process malformed PE headers that exceed the allocated buffer space, creating a potential exploitation vector for remote attackers.
The technical exploitation of this vulnerability follows a classic buffer overflow pattern where attacker-controlled data exceeds the bounds of a fixed-length buffer in memory. When ClamAV processes a maliciously crafted Upack PE file, the cli_scanpe function fails to properly validate the size of the PE header structure, allowing an attacker to overwrite adjacent memory locations. This memory corruption can lead to arbitrary code execution with the privileges of the scanning process, typically running with elevated permissions to scan potentially malicious files. The vulnerability is particularly dangerous because it can be triggered remotely through network-based file scanning operations, making it a significant threat to systems that process untrusted files automatically.
The operational impact of CVE-2008-1100 extends beyond simple code execution, as it represents a fundamental security flaw in the antivirus scanning infrastructure that protects against malware. Systems utilizing affected ClamAV versions become vulnerable to remote code execution attacks that could allow adversaries to gain complete control over the scanning host, potentially leading to broader network compromise. The vulnerability affects both network-based and file-based scanning operations, as the buffer overflow can occur regardless of whether the PE file is accessed through a network share, downloaded from a web source, or processed from local storage. Organizations relying on ClamAV for security operations face significant risk exposure, particularly those with automated scanning systems that process files from untrusted sources without proper validation.
Mitigation strategies for this vulnerability require immediate patching of affected ClamAV installations to versions that contain the necessary code fixes. The fix implemented by the ClamAV development team involves proper bounds checking and input validation within the cli_scanpe function to prevent buffer overflows when processing PE file headers. System administrators should also implement additional security controls such as restricting automatic scanning of untrusted files, implementing network segmentation to isolate scanning systems, and monitoring for unusual scanning behavior that might indicate exploitation attempts. From a defensive perspective, this vulnerability aligns with CWE-121, which describes buffer overflow conditions, and maps to ATT&CK technique T1059.007 for execution through command and scripting interpreter, as exploitation could lead to arbitrary code execution in the context of the scanning process. Organizations should also consider implementing network-based intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability pattern.