CVE-2004-0936 in Sophos
Summary
by MITRE
RAV antivirus 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 • 01/12/2025
The vulnerability described in CVE-2004-0936 represents a significant flaw in the RAV antivirus software's decompression and file analysis capabilities. This issue stems from the software's inability to properly validate compressed file structures, specifically when encountering archive files where both local and global headers are set to zero. The vulnerability operates at the core of how antivirus systems process and scan compressed files, which are commonly used by attackers to evade detection mechanisms. When a compressed file contains headers set to zero, the RAV antivirus fails to recognize this as a potentially malicious construct, allowing the file to pass through the security screening process unimpeded. This weakness directly impacts the fundamental security posture of systems relying on RAV protection, as it creates a bypass mechanism that adversaries can exploit without requiring sophisticated attack vectors. The flaw demonstrates a critical gap in the antivirus software's parsing logic and validation routines.
The technical implementation of this vulnerability involves the exploitation of how RAV handles compressed file formats, particularly those using the zip or similar compression standards. When the antivirus software encounters a compressed file with zeroed headers, it fails to properly identify the file as malformed or suspicious, thereby failing to apply appropriate scanning and analysis routines. This occurs because the software's decompression engine does not perform sufficient validation checks on header values before proceeding with file extraction and analysis. The zeroed headers create a condition where the antivirus software cannot properly determine the file's true nature or intended behavior, effectively allowing malicious payloads hidden within compressed archives to execute without detection. This vulnerability aligns with CWE-129, which addresses improper validation of input, and represents a classic case of inadequate bounds checking and header validation. The issue also relates to ATT&CK technique T1027, which covers obfuscated files or information, as attackers can leverage this weakness to create obfuscated payloads that bypass security controls.
The operational impact of CVE-2004-0936 extends beyond simple bypass capabilities, as it fundamentally undermines the trust placed in the antivirus solution's ability to protect against compressed file-based threats. Organizations using RAV antivirus software would experience a false sense of security when processing compressed files, leading to potential data breaches, system compromise, and unauthorized access to sensitive information. The vulnerability could be exploited in various attack scenarios including email-based attacks, web downloads, and file transfer operations where compressed archives are commonly used. Attackers could craft malicious compressed files with zeroed headers that would successfully bypass the antivirus protection, allowing malware to be deployed silently on target systems. This flaw particularly affects enterprise environments where compressed files are frequently processed and where the antivirus solution is expected to provide comprehensive protection. The vulnerability's persistence across multiple file types and compression formats makes it especially dangerous, as it could be leveraged across various attack vectors and delivery mechanisms.
Mitigation strategies for this vulnerability require immediate software updates and patches from the vendor, as well as enhanced monitoring and validation procedures. Organizations should implement additional layers of protection beyond the primary antivirus solution, including network-based intrusion detection systems and file integrity monitoring tools. The recommended approach includes updating to the latest version of RAV antivirus software that addresses the header validation issue, implementing strict file type and compression format policies, and conducting regular security assessments to identify similar vulnerabilities. System administrators should also consider implementing file reputation systems and behavioral analysis tools that can detect anomalous file behavior regardless of compression status. Additionally, organizations should establish robust incident response procedures that account for potential bypass scenarios and ensure comprehensive network monitoring to detect unauthorized access attempts. The vulnerability highlights the importance of maintaining current security software versions and implementing defense-in-depth strategies that do not rely solely on a single protection mechanism. Regular security testing and vulnerability assessments should be conducted to identify similar weaknesses in other security solutions and ensure comprehensive protection against evolving threats.