CVE-2003-0309 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.01, 5.5, and 6.0 allows remote attackers to bypass security zone restrictions and execute arbitrary programs via a web document with a large number of duplicate file:// or other requests that point to the program and open multiple file download dialogs, which eventually cause Internet Explorer to execute the program, as demonstrated using a large number of FRAME or IFRAME tags, aka the "File Download Dialog Vulnerability."
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Analysis
by VulDB Data Team • 03/16/2025
This vulnerability represents a sophisticated privilege escalation mechanism that exploited fundamental flaws in Microsoft Internet Explorer's handling of local file references and security zone enforcement. The flaw specifically affected Internet Explorer versions 5.01, 5.5, and 6.0, creating a critical security gap that allowed remote attackers to circumvent the browser's security model designed to prevent execution of local programs from web content. The vulnerability operates through a technique that leverages the browser's file download dialog mechanism to execute arbitrary code, fundamentally undermining the security boundaries between web content and local system resources.
The technical implementation of this vulnerability relies on the manipulation of HTML elements such as FRAME and IFRAME tags to generate an excessive number of file:// protocol requests. When Internet Explorer processes these requests, it opens multiple file download dialogs that eventually lead to program execution, bypassing the normal security restrictions that should prevent local file access from web-based content. This mechanism exploits the browser's failure to properly validate and limit the number of concurrent file access requests, creating a scenario where legitimate security controls are overwhelmed and rendered ineffective. The vulnerability demonstrates a clear weakness in the browser's resource management and security enforcement mechanisms, specifically in how it handles local file system interactions through web-based interfaces.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with the ability to execute arbitrary programs on vulnerable systems without user interaction beyond visiting a malicious webpage. This creates a significant risk for enterprise environments where users may inadvertently browse to compromised websites, leading to potential system compromise and data exfiltration. The vulnerability's exploitation does not require any special user privileges or complex attack vectors, making it particularly dangerous in corporate and government environments where users frequently access web content from untrusted sources. The attack chain essentially transforms a web browsing activity into a system compromise event, leveraging the browser's legitimate file access capabilities against the system's security model.
The vulnerability aligns with CWE-264, which describes "Permissions, Privileges, and Access Controls" issues, and demonstrates how improper access control enforcement can lead to privilege escalation. From an ATT&CK perspective, this vulnerability maps to T1059.005 for "Command and Scripting Interpreter: Visual Basic" and T1068 for "Exploitation for Privilege Escalation," as it enables attackers to execute programs with elevated privileges through browser-based exploitation. Organizations affected by this vulnerability faced significant challenges in mitigating the risk, as the exploit required no user interaction beyond normal web browsing and could be delivered through various web-based attack vectors. The remediation approach necessitated immediate patch deployment, browser security configuration changes, and user education regarding safe browsing practices. This vulnerability highlighted the importance of robust input validation and resource management in web browsers, particularly concerning local file system access controls and the enforcement of security boundaries between different execution contexts.