CVE-2008-5528 in eSafe
Summary
by MITRE
Aladdin eSafe 7.0.17.0, 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 described in CVE-2008-5528 represents a significant bypass mechanism within Aladdin eSafe 7.0.17.0 antivirus software when operating in conjunction with Internet Explorer 6 or 7 browsers. This flaw exploits the heuristic detection capabilities of the antivirus solution by manipulating file characteristics that are typically used to identify malicious content. The vulnerability specifically targets the way eSafe processes and analyzes HTML documents that contain embedded executable code, creating a scenario where legitimate security measures fail to recognize the presence of malware.
The technical implementation of this vulnerability relies on the manipulation of file headers and extensions to circumvent signature-based and heuristic detection systems. By placing an MZ header at the beginning of an HTML document, attackers can trick the antivirus software into treating the file as an executable rather than a web document. The MZ header is the standard marker for windows executable files, which creates confusion in the detection algorithms that rely on file extension and header analysis. The filename modification techniques involve removing the extension entirely or changing it to .txt or .jpg, exploiting the fact that many antivirus solutions perform content analysis based on file type indicators that may not be properly validated against the actual file structure.
The operational impact of this vulnerability extends beyond simple malware evasion, as it demonstrates a fundamental weakness in how antivirus software handles file type identification and content analysis. When Internet Explorer 6 or 7 processes HTML documents containing such manipulated files, the browser's security model interacts with eSafe's detection mechanisms in a way that allows malicious content to slip through security controls. This creates a dangerous scenario where users may be exposed to exploits like CVE-2006-5745, which targets vulnerabilities in Microsoft's handling of certain file formats. The vulnerability essentially transforms a document that should be treated as benign HTML into a potentially malicious executable, bypassing the security controls that would normally detect and block such threats.
This vulnerability aligns with several common attack patterns documented in the ATT&CK framework, particularly those involving evasion techniques and credential access. The method of manipulating file headers and extensions represents a classic fileless malware technique that can be categorized under T1070.004 (Fileless Malware) and T1566 (Phishing). From a CWE perspective, this vulnerability relates to CWE-20: Improper Input Validation, as the antivirus system fails to properly validate file characteristics before processing content. The issue also reflects CWE-347: Improper Verification of Cryptographic Signature, since the system does not adequately verify file integrity or structure. The attack vector specifically demonstrates how a lack of proper file type validation can allow attackers to manipulate security controls through simple header manipulation, creating a scenario where security software becomes ineffective against carefully crafted malicious content.
Organizations affected by this vulnerability should implement immediate mitigations including updating to newer versions of eSafe antivirus software, implementing additional network-based detection measures, and establishing more robust content filtering policies. The recommended approach involves deploying multiple layers of security controls that do not rely solely on file extension or header analysis, including behavior-based detection systems and network traffic monitoring. Security teams should also consider implementing strict content validation policies for email attachments and web downloads, particularly when dealing with legacy systems running Internet Explorer 6 or 7. The vulnerability highlights the importance of defense in depth strategies and the need for security solutions that can properly analyze file content regardless of file naming conventions or header manipulation techniques.