CVE-2004-0937 in Sophos
Summary
by MITRE
Sophos Anti-Virus before 3.87.0, and Sophos Anti-Virus for Windows 95, 98, and Me before 3.88.0, allows remote attackers to bypass antivirus protection via a compressed file with both local and global headers set to zero, which does not prevent the compressed file from being opened on a target system.
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Analysis
by VulDB Data Team • 11/21/2024
This vulnerability exists in Sophos Anti-Virus software versions prior to 3.87.0 for general systems and 3.88.0 for Windows 95, 98, and Me operating systems. The flaw represents a critical weakness in the decompression and file analysis mechanisms of the antivirus solution, specifically affecting how the software handles compressed files with malformed headers. The vulnerability stems from insufficient validation of compressed file structures, particularly when both local and global headers are set to zero values, which should normally indicate corrupted or malicious file formats.
The technical implementation of this vulnerability exploits a fundamental flaw in the decompression engine's header parsing logic. When a compressed file contains both local and global headers set to zero, the antivirus software fails to properly identify this as a suspicious or potentially malicious file structure. This condition bypasses the normal detection mechanisms that would typically flag such malformed files as potential threats. The zero header values create a scenario where the decompression process continues without proper validation, allowing the malicious payload to be extracted and executed on the target system.
From an operational perspective, this vulnerability creates a significant risk for organizations using affected Sophos Anti-Virus versions, as it allows remote attackers to deliver malicious payloads that would otherwise be detected by standard antivirus protection. The attack vector is particularly dangerous because it can be executed through compressed file formats commonly used in email attachments, file downloads, or network transfers. The vulnerability effectively creates a bypass mechanism that renders the antivirus protection ineffective against specifically crafted compressed files, potentially allowing malware to execute without detection.
The impact of this vulnerability aligns with CWE-129, which addresses insufficient input validation, and can be mapped to ATT&CK technique T1059.007 for execution through compressed files. Organizations exposed to this vulnerability face potential compromise of endpoint systems, data exfiltration, and lateral movement capabilities for attackers who can leverage this bypass. The vulnerability is particularly concerning in environments where compressed files are frequently processed, as it provides a reliable method for evading security controls.
Mitigation strategies should focus on immediate software updates to versions 3.87.0 or later for general systems and 3.88.0 for Windows 95, 98, and Me systems. Organizations should also implement additional network-level protections such as content filtering and email scanning to detect potentially malicious compressed files. Network administrators should consider implementing strict file type controls and monitoring for unusual compressed file activity. Regular security assessments and vulnerability scanning should be conducted to identify any remaining systems that may still be vulnerable to this specific header manipulation attack.