CVE-2005-3222 in VBA32 Antivirus
Summary
by MITRE
Multiple interpretation error in unspecified versions of VBA32 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 • 07/28/2017
The vulnerability described in CVE-2005-3222 represents a critical flaw in the VBA32 Antivirus software that demonstrates a fundamental weakness in how antivirus solutions handle file format parsing and validation. This issue stems from an interpretation error that occurs during the analysis of compressed archive files, specifically RAR format archives that contain malicious executables. The flaw exists in the way VBA32 processes the central and local headers within RAR files, which are critical components that define the structure and contents of archive files. When attackers craft RAR files with malformed headers that still maintain compatibility with legitimate archive tools like WinRAR and PowerZip, they can exploit this inconsistency in validation logic to bypass antivirus detection mechanisms.
The technical implementation of this vulnerability exploits the differences in how various archive utilities interpret and validate RAR file structures. While tools such as WinZip and BitZipper correctly identify the malformed headers as corrupted and reject the files, VBA32 fails to properly validate these headers during its scanning process. This discrepancy creates a window of opportunity where malicious executables can be embedded within RAR archives that appear legitimate to the antivirus software. The vulnerability specifically targets the parsing logic that examines the central directory structure of RAR files, where the central header contains metadata about all files within the archive. When these headers contain malformed data or invalid offsets, legitimate archive utilities may still attempt to extract the contents, while antivirus scanners might skip the validation entirely or misinterpret the malformed structure as valid.
The operational impact of this vulnerability is significant as it allows remote attackers to conduct targeted attacks against systems protected by VBA32 Antivirus without triggering security alerts. The attack vector relies on the attacker's ability to create RAR files that maintain structural compatibility with legitimate archive tools while containing malicious payloads that evade detection. This creates a dangerous scenario where users can safely open and extract files using standard tools like WinRAR or PowerZip, but the same files remain undetected by the antivirus protection. The vulnerability essentially creates a false sense of security where users believe they are operating in a secure environment due to the successful extraction of files, while simultaneously exposing their systems to potential malware infection. Organizations relying on VBA32 Antivirus for protection are particularly vulnerable to this attack as they may not be aware that their security measures are being circumvented.
This vulnerability aligns with CWE-129, which addresses improper validation of input data, and demonstrates how insufficient input validation in file format parsers can lead to security bypasses. The flaw also relates to ATT&CK technique T1059.007 for execution through command and scripting interpreter, as the malicious payloads can be executed through the legitimate archive extraction process. The vulnerability represents a classic case of inconsistent validation logic where different software components interpret the same malformed data differently, creating exploitable gaps in security. Organizations should implement layered security approaches that include multiple validation points and cross-checking mechanisms to prevent similar bypasses. The incident highlights the importance of thorough testing across different software implementations and the need for comprehensive validation that considers how various tools interpret and handle malformed data structures. This vulnerability also underscores the necessity of keeping antivirus solutions updated, as such parsing inconsistencies are typically addressed through software patches that improve header validation logic and ensure more consistent behavior across different file format interpretations.