CVE-2005-3233 in Trustix
Summary
by MITRE
Multiple interpretation error in unspecified versions of Trustix Antivirus allows remote attackers to bypass virus detection via a malicious executable in a specially crafted RAR file with malformed central and local headers, which can still be opened by products such as Winrar and PowerZip, even though they are rejected as corrupted by Winzip and BitZipper.
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Analysis
by VulDB Data Team • 07/30/2017
The vulnerability described in CVE-2005-3233 represents a critical flaw in Trustix Antivirus software that demonstrates the complexities of file format parsing and antivirus detection mechanisms. This issue stems from how the antivirus engine interprets archive files, specifically RAR archives, which are widely used for file compression and distribution across various platforms. The vulnerability manifests when the antivirus system encounters a specially crafted RAR file containing malformed central and local headers that would normally be rejected by standard archive utilities like Winzip and BitZipper, yet these same archives can still be successfully opened by other tools such as Winrar and PowerZip, creating a significant discrepancy in how different software handles the same file format.
The technical root cause of this vulnerability lies in the inconsistent interpretation of RAR file structures within the Trustix Antivirus engine. When processing a maliciously crafted RAR file, the antivirus system fails to properly validate the archive's internal structure, particularly the central directory and local file headers that define how the archive should be read and interpreted. This parsing inconsistency allows attackers to construct RAR files that contain executable code disguised within malformed headers, effectively bypassing the antivirus detection mechanisms that rely on standard file format validation. The vulnerability specifically targets the way the antivirus engine handles these headers, which are typically used to describe the contents and structure of the archive, but in this case are manipulated to hide malicious payloads.
The operational impact of this vulnerability extends beyond simple bypass of antivirus protection, as it demonstrates a fundamental flaw in how security software handles file format validation and interpretation. Attackers can exploit this weakness by creating RAR archives that appear legitimate to standard archive utilities but contain hidden malicious code that the Trustix Antivirus fails to detect. This creates a dangerous scenario where users can successfully open and execute files that should be flagged as suspicious or malicious by their antivirus software. The vulnerability essentially creates a false sense of security, as the antivirus system incorrectly assumes that files that can be opened by other tools are safe, while simultaneously failing to detect the malicious content within those same files.
This vulnerability aligns with several cybersecurity frameworks and threat modeling approaches, particularly those addressing software robustness and input validation issues. From a CWE perspective, this vulnerability relates to CWE-129, which addresses insufficient validation of the length or size of input data, and CWE-131, which covers improper handling of buffer sizes in input processing. The attack pattern follows ATT&CK framework techniques such as T1059 for execution through command and scripting interpreter and T1204 for user execution, as the malicious payload would typically be executed through legitimate archive extraction processes. The vulnerability also demonstrates the importance of defensive programming practices and the need for comprehensive testing across multiple platforms and tools to ensure consistent security behavior.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both the immediate issue and broader security implications. Organizations should immediately update their Trustix Antivirus software to versions that properly handle malformed RAR headers, while also implementing additional verification mechanisms such as multiple antivirus engines for file analysis, and employing behavioral monitoring to detect suspicious file extraction activities. Network administrators should consider implementing additional file type restrictions and content filtering measures, particularly for archive files, and ensure that all archive utilities within the organization are kept up to date with the latest security patches. The vulnerability also highlights the importance of maintaining diverse security toolsets that can cross-verify each other's detections, as relying on a single antivirus solution may leave organizations vulnerable to such interpretation errors. Regular security assessments should include testing of file format handling capabilities across different software implementations to identify similar inconsistencies that could be exploited by attackers.