CVE-2008-5548 in VirusBuster
Summary
by MITRE
VirusBuster 4.5.11.0, 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 • 10/22/2018
The vulnerability identified as CVE-2008-5548 represents a significant bypass mechanism within VirusBuster 4.5.11.0 antivirus software that specifically affects users operating Internet Explorer 6 or 7 browsers. This flaw exploits the way security software processes and analyzes file types, creating a pathway for malicious actors to evade detection by manipulating file headers and extensions. The vulnerability operates through a sophisticated technique that leverages the fundamental structure of executable files while disguising their true nature through filename manipulation.
The technical implementation of this vulnerability relies on the presence of an MZ header at the beginning of HTML documents, which is the standard signature found at the start of executable files in the windows operating system. The MZ header, named after the initials of the first executable file format used in ms-dos systems, serves as a critical identifier that antivirus software uses to recognize potentially malicious code. When VirusBuster encounters an HTML document containing this MZ header, it incorrectly interprets the file as an executable rather than a web document, leading to the bypass of security checks. This manipulation occurs because the software fails to properly validate the file's actual content against its declared type, creating a false positive detection scenario.
The operational impact of this vulnerability extends beyond simple evasion techniques, as it allows attackers to deliver malicious payloads through seemingly benign HTML documents that are commonly encountered in web browsing environments. The demonstration of this vulnerability using CVE-2006-5745 exploit highlights the severity of the issue, as this particular exploit targets vulnerabilities in microsoft office applications that could lead to remote code execution. By modifying the filename to remove or alter its extension, attackers can trick both the antivirus software and the user into believing they are dealing with harmless text or image files. This technique specifically targets the heuristic analysis capabilities of VirusBuster, which rely heavily on file extension matching and header inspection to identify threats.
The vulnerability demonstrates a classic case of insufficient input validation and improper file type detection, which aligns with common weakness patterns described in the common weakness enumeration catalog. This flaw represents a failure in the software's ability to perform proper content analysis and type determination, falling short of established security standards for robust threat detection mechanisms. From an att&ck framework perspective, this vulnerability maps to techniques involving evasion and defense evasion tactics, specifically targeting the detection capabilities of endpoint protection solutions. The attack vector leverages user trust in familiar file formats while exploiting the security software's inability to properly correlate file headers with actual content behavior.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both the immediate software limitation and broader security practices. Organizations should ensure that VirusBuster is updated to versions that properly handle file type detection and header validation, while also implementing additional security measures such as web application firewalls and content inspection systems. The vulnerability underscores the importance of proper file type validation and the need for security software to maintain robust heuristic analysis capabilities that do not rely solely on filename extensions. Network administrators should consider implementing additional layers of protection such as email filtering, web proxy inspection, and application whitelisting to reduce the impact of such evasion techniques. Regular security assessments and vulnerability scanning should include checks for similar issues in other antivirus solutions to ensure comprehensive protection against file-type manipulation attacks.