CVE-2008-5547 in ViRobot
Summary
by MITRE
HAURI ViRobot 2008.12.4.1499 and possibly 2008.9.12.1375, 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 described in CVE-2008-5547 represents a significant bypass mechanism within HAURI ViRobot 2008 antivirus software that specifically targets the way the system handles file detection when Internet Explorer 6 or 7 is in use. This flaw demonstrates a critical weakness in the antivirus product's heuristic analysis capabilities and file extension handling logic, creating a pathway for attackers to evade detection of malicious content. The vulnerability exploits the fundamental assumption that file extensions serve as reliable indicators of file type and content, which is a core principle in cybersecurity defense mechanisms. The attack vector specifically leverages the interaction between the antivirus software and the web browser environment, highlighting how browser-based security can be undermined when endpoint protection systems fail to properly validate file content regardless of extension.
The technical implementation of this vulnerability involves placing an MZ header at the beginning of an HTML document, which is the standard signature found at the start of executable files. This technique exploits the fact that many antivirus systems perform content analysis based on file headers and signatures rather than relying solely on file extensions. The MZ header, typically found at the beginning of windows executable files, when present at the start of an HTML document, can cause the antivirus software to misinterpret the file type and potentially bypass detection mechanisms. The filename modification aspect of this attack involves changing the file extension to either no extension, .txt, or .jpg, which are all common extensions that antivirus systems may not aggressively scan or may scan with reduced scrutiny. This approach aligns with the concept of file extension manipulation, which is a well-documented evasion technique in cybersecurity and is often categorized under attack patterns that exploit application logic flaws.
The operational impact of this vulnerability extends beyond simple malware delivery, as it represents a complete bypass of the antivirus detection system's ability to properly analyze content. When an attacker successfully employs this technique, they can deliver a document containing a CVE-2006-5745 exploit without the antivirus system recognizing the malicious nature of the content. This creates a dangerous scenario where users may be exposed to significant security risks, as the antivirus software fails to properly identify and block the malicious content. The vulnerability is particularly concerning because it leverages the trust relationship between the browser and the antivirus system, where the browser may be more lenient with certain file types, especially those commonly associated with legitimate content like images or text files. This flaw essentially allows attackers to transform potentially suspicious executable content into seemingly benign files that bypass security controls. The attack demonstrates how a single logic flaw in antivirus signature analysis can result in complete bypass of protection mechanisms, potentially exposing systems to various threats including but not limited to the specific CVE-2006-5745 exploit mentioned in the description.
The security implications of this vulnerability align with several established frameworks and attack patterns. From a CWE perspective, this represents a weakness in input validation and file type handling, specifically related to improper handling of file headers and extensions. The vulnerability demonstrates characteristics of CWE-20, which deals with improper input validation, and CWE-502, which addresses deserialization of untrusted data. The technique used to bypass detection also relates to ATT&CK tactics such as T1059 (Command and Scripting Interpreter) and T1204 (User Execution), as it relies on tricking users into executing malicious content through seemingly benign file types. The attack pattern follows principles of fileless malware delivery and extension-based evasion, which are common techniques in modern cyber attacks. Organizations using affected versions of HAURI ViRobot would be particularly vulnerable to attacks that combine this evasion technique with other exploitation methods, creating a multi-layered attack approach that could circumvent traditional security controls. The vulnerability underscores the importance of robust content analysis capabilities in antivirus systems, particularly in environments where web browsers are actively involved in content delivery and execution. This flaw highlights the need for comprehensive file analysis that goes beyond simple extension matching and includes thorough content inspection regardless of file type indicators.