CVE-2005-3224 in Antivir Personal
Summary
by MITRE
Multiple interpretation error in unspecified versions of AntiVir 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
This vulnerability represents a critical flaw in AntiVir Antivirus software that demonstrates the complexities of file format parsing and antivirus signature validation. The issue stems from how the antivirus engine interprets RAR archive files, specifically targeting the handling of malformed central and local headers within these compressed archives. The vulnerability operates at the intersection of file format specification compliance and security boundary enforcement, where legitimate archive tools like WinRAR and PowerZip successfully process these malformed files while more restrictive tools such as WinZip and BitZipper reject them as corrupted. This discrepancy creates a dangerous gap in security coverage where malicious executables can evade detection by exploiting the lenient parsing behavior of AntiVir's engine.
The technical implementation of this vulnerability exploits the fundamental mismatch between how different archive utilities handle malformed file headers. When a RAR file contains specially crafted central and local headers that violate standard specifications, the behavior diverges significantly across different software implementations. AntiVir's antivirus engine appears to implement a more permissive parsing strategy that accepts these malformed headers, allowing the embedded malicious executable to pass through the scanning process. This parsing error creates an interpretation gap where the antivirus fails to properly validate the archive structure, leading to potential execution of malicious code that would otherwise be detected if the file were properly rejected by the antivirus engine. The vulnerability specifically affects the archive header parsing mechanism, which is a common attack surface in antivirus software due to the complexity of supporting multiple archive formats.
The operational impact of this vulnerability extends beyond simple bypass of virus detection, representing a broader security risk in endpoint protection systems. Attackers can leverage this flaw to deliver malware through seemingly legitimate compressed archives that successfully pass through AntiVir's scanning process while maintaining their malicious payload. The vulnerability creates a false sense of security for users relying on AntiVir, as the antivirus appears to function normally while silently failing to detect threats. This type of vulnerability directly impacts the principle of defense in depth, where multiple security layers should provide overlapping protection. The attack vector demonstrates how a single parsing error in one component of a security system can create a complete bypass of protection mechanisms, potentially allowing for privilege escalation or data exfiltration attacks. Organizations using AntiVir in enterprise environments face significant risk as this vulnerability could enable advanced persistent threats to establish footholds within networks.
Mitigation strategies for this vulnerability should focus on immediate software updates and comprehensive security assessments. The primary remediation involves updating to patched versions of AntiVir Antivirus that properly implement strict header validation and reject malformed RAR archives. Security administrators should implement additional layers of protection including network-based intrusion detection systems that monitor for suspicious archive extraction patterns and behavioral analysis tools that detect anomalous execution patterns. The vulnerability highlights the importance of adhering to secure coding practices and implementing comprehensive input validation, which aligns with common weakness enumeration CWE-129 and the ATT&CK framework's technique T1070 for indicator removal and T1059 for command and scripting interpreter. Organizations should also consider implementing sandboxing techniques for suspicious archive files and establishing network segmentation to limit the potential impact of successful exploitation. Regular security assessments and vulnerability scanning should include testing for similar parsing errors across other antivirus and security tools to ensure comprehensive protection against similar vulnerabilities in the broader security ecosystem.