CVE-2005-3227 in Antivir
Summary
by MITRE
Multiple interpretation error in unspecified versions of UNA 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 • 07/29/2017
The vulnerability described in CVE-2005-3227 represents a critical flaw in UNA Antivirus software that demonstrates the complex nature of file format interpretation errors in antivirus systems. This issue stems from how the antivirus software processes and validates RAR archive files, specifically targeting the central and local headers that define the structure and contents of compressed archives. The flaw occurs when the antivirus engine encounters a specially crafted RAR file that contains malformed headers, yet these files remain functional in legitimate archive applications like WinRAR and PowerZip, creating a dangerous discrepancy in file validation approaches. The vulnerability highlights the fundamental challenge that antivirus vendors face in maintaining consistent and robust file format parsing across different archive types and versions.
The technical root cause of this vulnerability lies in the improper handling of malformed RAR file structures during the decompression and analysis phases of antivirus scanning. When UNA Antivirus encounters a RAR file with corrupted central and local headers, the software's parsing logic fails to properly validate these structures according to the RAR specification standards. This misinterpretation allows attackers to craft malicious executables that can bypass detection mechanisms because the antivirus system either misclassifies the file structure or fails to properly extract and analyze the contained malicious payload. The vulnerability operates at the intersection of file format specification compliance and security validation, where legitimate archive tools can process malformed files while security tools cannot, creating an exploitation window.
The operational impact of this vulnerability extends beyond simple bypass of antivirus protection, as it demonstrates a systematic failure in how security tools handle edge cases in file format parsing. Attackers can leverage this weakness to deliver malware through seemingly legitimate RAR archives that appear valid to standard archive utilities but contain hidden malicious code that evades detection. This creates a significant risk for organizations that rely on traditional signature-based detection methods, as the vulnerability allows for the delivery of payloads that would otherwise be flagged by more robust validation systems. The issue also reflects poorly on the overall security posture of systems using UNA Antivirus, as it provides an attack vector that can be exploited without requiring sophisticated techniques or knowledge of specific system internals.
Mitigation strategies for this vulnerability should focus on comprehensive input validation and robust error handling within antivirus engines. Organizations should implement multiple layers of protection including updated antivirus signatures, enhanced heuristic analysis capabilities, and regular security updates to address known vulnerabilities in archive processing. The remediation approach must include thorough testing of antivirus behavior against malformed files and implementation of strict validation routines that can identify and reject suspicious archive structures before they can be processed. Additionally, system administrators should consider implementing network-based intrusion detection systems that can monitor for unusual archive extraction patterns and maintain awareness of the specific RAR format vulnerabilities that may affect their security infrastructure. This vulnerability underscores the importance of following industry standards such as those defined in CWE categories related to input validation and file format parsing, while also aligning with ATT&CK techniques that focus on evasion and execution through legitimate system utilities.