CVE-2008-5544 in The Hacker
Summary
by MITRE
Hacksoft The Hacker 6.3.1.2.174 and possibly 6.3.0.9.081, when Internet Explorer 6 or 7 is used, allows remote attackers to bypass detection of malware in an HTML document by placing an MZ header (aka "EXE info") at the beginning, and modifying the filename to have (1) no extension, (2) a .txt extension, or (3) a .jpg extension, as demonstrated by a document containing a CVE-2006-5745 exploit.
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Analysis
by VulDB Data Team • 11/27/2017
The vulnerability described in CVE-2008-5544 represents a sophisticated bypass mechanism targeting security detection systems within Internet Explorer environments. This flaw specifically affects Hacksoft The Hacker versions 6.3.1.2.174 and potentially 6.3.0.9.081, creating a critical pathway for malware delivery that exploits the browser's file type recognition and content inspection mechanisms. The attack vector leverages the inherent weaknesses in how security software processes and validates file signatures, particularly when dealing with HTML documents that contain embedded malicious payloads. The vulnerability demonstrates a fundamental flaw in file extension-based detection methodologies that rely heavily on visual file naming conventions rather than comprehensive content analysis.
The technical implementation of this vulnerability involves the strategic placement of an MZ header at the beginning of HTML documents, effectively creating a deceptive file structure that confuses security detection systems. The MZ header, traditionally associated with executable files, serves as a signature that can trigger different processing behaviors within the security software. By modifying the filename to remove its extension entirely or by appending .txt or .jpg extensions, attackers exploit the tendency of security systems to rely on file extensions as primary indicators of file type rather than examining actual content. This technique allows malware to bypass signature-based detection mechanisms that would normally identify malicious content when it appears in standard executable formats, instead permitting it to be processed as benign text or image files.
The operational impact of this vulnerability extends beyond simple detection bypass, creating a comprehensive security gap that affects multiple layers of defense. When Internet Explorer 6 or 7 processes HTML documents with these modified file structures, the browser's security policies fail to properly identify the malicious content, leading to potential execution of exploits such as CVE-2006-5745. This vulnerability represents a classic example of a file extension manipulation attack that can be classified under CWE-20, "Improper Input Validation," and specifically aligns with ATT&CK technique T1059.005 for execution through command and scripting interpreter. The attack demonstrates how attackers can leverage browser-specific security gaps to circumvent content inspection systems, potentially leading to successful exploitation of other vulnerabilities within the same attack chain.
Security professionals addressing this vulnerability must implement comprehensive content inspection mechanisms that do not rely solely on file extensions or visual naming conventions. The mitigation strategies should focus on implementing robust file signature analysis that examines actual content headers and structures rather than merely trusting file extension indicators. Organizations should deploy security solutions that perform deep content analysis regardless of file naming conventions, ensuring that HTML documents containing MZ headers are properly identified and quarantined. This vulnerability underscores the critical importance of defense in depth approaches, where multiple layers of security validation are implemented to prevent bypass attempts that exploit single-point failures in detection methodologies. The issue also highlights the necessity of regular security updates and the importance of moving away from extension-based detection systems that can be easily circumvented through simple file manipulation techniques.