CVE-2003-1041 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.x and 6.0 allows remote attackers to execute arbitrary programs via a modified directory traversal attack using a URL containing ".." (dot dot) sequences and a filename that ends in "::" which is treated as a .chm file even if it does not have a .chm extension. NOTE: this bug may overlap CVE-2004-0475.
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Analysis
by VulDB Data Team • 02/02/2025
This vulnerability represents a critical directory traversal flaw in Microsoft Internet Explorer versions 5.x and 6.0 that enables remote code execution through carefully crafted malicious URLs. The vulnerability exploits the browser's handling of file paths where directory traversal sequences ".." combined with filenames ending in "::" are interpreted as compressed help files regardless of their actual file extension. This creates a dangerous condition where attackers can bypass normal file access restrictions and execute arbitrary programs on vulnerable systems. The flaw specifically leverages the Windows shell integration mechanism that automatically associates "::" suffixes with compressed help files, allowing malicious payloads to be executed without proper validation of file types. This vulnerability is classified under CWE-22 as a directory traversal attack and represents a classic example of insufficient input validation in file path handling mechanisms.
The technical exploitation occurs when Internet Explorer processes a URL containing directory traversal sequences followed by a filename ending in "::" which the browser treats as a .chm (Compiled HTML Help) file even though it lacks the proper extension. This misinterpretation allows attackers to craft malicious URLs that can execute code through the Windows help system. The vulnerability operates at the application layer and requires no special privileges to exploit, making it particularly dangerous in web environments. The attack vector relies on the browser's automatic file type detection and association mechanisms rather than direct code injection, which makes detection more challenging for security systems. According to ATT&CK framework, this represents a technique categorized under T1203 - Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute code on target systems.
The operational impact of this vulnerability extends beyond simple code execution to include potential system compromise and data exfiltration. Attackers can use this flaw to install malware, create backdoors, or perform privilege escalation attacks on vulnerable systems. The vulnerability affects a broad range of Windows systems running Internet Explorer 5.x and 6.0, which were widely deployed in enterprise environments during the early 2000s. Organizations with legacy systems running these browser versions face significant risk exposure, as the vulnerability can be exploited through web-based attacks without user interaction once a malicious URL is visited. The overlap with CVE-2004-0475 indicates that similar directory traversal mechanisms existed in other Microsoft products, suggesting a systemic issue in how Windows applications handle file path traversal operations. The vulnerability demonstrates the importance of proper input validation and the dangers of relying on file extension-based type detection rather than content-based validation.
Mitigation strategies for this vulnerability include immediate browser updates to supported versions, implementation of proper network filtering to block malicious URLs containing directory traversal sequences, and deployment of web application firewalls that can detect and block such attacks. Organizations should also implement security awareness training to prevent users from visiting suspicious websites and ensure that automatic execution of help files is disabled. The most effective long-term solution involves migrating away from legacy Internet Explorer versions to modern browsers with proper security controls and regular update mechanisms. Network administrators should monitor for traffic patterns containing suspicious URL sequences and implement content filtering solutions that can identify and block malicious directory traversal attempts. This vulnerability highlights the importance of defense in depth strategies and the necessity of maintaining up-to-date security patches across all system components to prevent exploitation of known vulnerabilities.