CVE-2008-5532 in Ikarus Antivirus
Summary
by MITRE
Ikarus Virus Utilities T3.1.1.45.0 and possibly T3.1.1.34.0, 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 • 12/05/2017
The vulnerability described in CVE-2008-5532 represents a significant bypass mechanism within Ikarus Virus Utilities version 3.1.1.45.0 and potentially earlier versions 3.1.1.34.0, specifically targeting the behavior of Internet Explorer 6 and 7 browsers. This flaw exploits the way antivirus software interacts with file extensions and headers during malware detection processes, creating a dangerous pathway for malicious actors to evade security measures. The vulnerability demonstrates how traditional signature-based detection systems can be circumvented through careful manipulation of file attributes that are typically considered innocuous by security applications. The technical implementation involves placing an MZ header, which is the standard executable file signature used by windows operating systems, at the beginning of HTML documents. This header is commonly associated with executable files and would normally trigger immediate alert mechanisms in antivirus software when encountered in file contexts where such signatures are inappropriate. The attack vector leverages the fact that when Internet Explorer processes HTML documents, it may interpret the presence of an MZ header in combination with specific filename extensions as a legitimate executable file rather than a malicious document, allowing the embedded malware to bypass detection protocols.
The operational impact of this vulnerability extends beyond simple evasion techniques to represent a fundamental weakness in how antivirus engines process file attributes and browser behaviors. When an attacker constructs a document with an MZ header at the beginning and modifies the filename to remove the typical executable extension or use innocuous extensions like .txt or .jpg, the antivirus system becomes confused about the file's true nature. This confusion occurs because traditional antivirus detection relies heavily on file extension matching combined with header analysis, and the combination of these manipulated elements creates a false positive scenario where the system fails to recognize the malicious intent. The vulnerability is particularly dangerous when combined with known exploits like CVE-2006-5745, which targets Internet Explorer vulnerabilities, creating a multi-layered attack that can potentially execute malicious code without triggering security alerts. This technique directly relates to CWE-119, which addresses weaknesses in the handling of buffer access and memory management, and also aligns with ATT&CK technique T1059.005 for command and scripting interpreter, as the bypassed detection allows for execution of malicious payloads through browser-based attack vectors. The attack demonstrates how simple file attribute manipulation can undermine complex security architectures.
The mitigation strategies for this vulnerability require comprehensive approaches that address both the immediate detection bypass and the underlying architectural weaknesses in how antivirus systems process file attributes. Organizations should implement multi-layered detection mechanisms that do not rely solely on file extensions and header signatures, instead employing behavioral analysis and heuristic scanning to identify suspicious patterns regardless of file naming conventions. Security administrators must ensure that antivirus engines are updated to recognize such evasion techniques and that signature databases include patterns for detecting manipulated headers in non-executable file contexts. The solution also involves implementing proper file extension validation at the network level and within browser security policies, preventing automatic execution of files with suspicious attributes regardless of their apparent file type. Additionally, regular security assessments should include testing for similar bypass techniques, and network monitoring systems should be configured to flag unusual combinations of file headers and extensions that might indicate attempted evasion. This vulnerability highlights the critical importance of maintaining up-to-date security measures and implementing defense-in-depth strategies that do not rely on single points of failure in detection mechanisms, as outlined in the NIST cybersecurity framework and ISO/IEC 27001 standards for information security management.