CVE-2003-0446 in Internet Explorer
Summary
by MITRE
Cross-site scripting (XSS) in Internet Explorer 5.5 and 6.0, possibly in a component that is also used by other Microsoft products, allows remote attackers to insert arbitrary web script via an XML file that contains a parse error, which inserts the script in the resulting error message.
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Analysis
by VulDB Data Team • 03/18/2025
This vulnerability represents a classic cross-site scripting flaw that specifically targeted Microsoft Internet Explorer versions 5.5 and 6.0, with potential implications for other Microsoft products utilizing the same underlying component. The vulnerability stems from how Internet Explorer processes XML files containing parse errors, creating a scenario where malicious script code can be injected into error messages displayed to users. This type of vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically manifesting as an error message injection vector rather than traditional input validation bypass.
The technical mechanism involves the XML parser component within Internet Explorer encountering malformed XML data that results in a parse error. When this error occurs, the parser generates an error message that includes the malformed content without proper sanitization or encoding. Attackers can craft XML files containing specially designed script code within elements that will cause parsing failures, thereby inserting executable JavaScript or other malicious code into the error message that gets rendered in the browser. This vulnerability is particularly dangerous because it leverages the browser's built-in XML processing capabilities rather than requiring user interaction with malicious web pages directly.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary code within the context of a user's browser session. This can lead to session hijacking, credential theft, data exfiltration, and other malicious activities that compromise user security. The vulnerability affects not just individual users but potentially entire organizations since it can be exploited through email attachments, web downloads, or any mechanism that delivers XML content to affected browsers. The fact that this vulnerability may affect other Microsoft products using the same XML parsing component means that the attack surface extends beyond just Internet Explorer, potentially impacting Microsoft Office applications and other software that rely on the same parsing engine.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1566 for Phishing, as attackers can leverage it to execute malicious scripts through crafted XML files delivered via phishing campaigns or malicious attachments. The vulnerability demonstrates the importance of proper input validation and output encoding in XML processing components, as highlighted by CWE-116 which addresses the improper encoding of data in XML parsers. Organizations should implement comprehensive security measures including browser hardening, XML content filtering, and user education to mitigate this risk.
Mitigation strategies should focus on both immediate remediation and long-term security improvements. Microsoft released security patches for this vulnerability, and organizations should ensure all affected systems are updated promptly. Additionally, implementing proper XML validation and sanitization processes, using Content Security Policy headers, and deploying web application firewalls can help prevent exploitation. Network-level filtering of XML content and email security solutions should also be considered to prevent malicious XML files from reaching users. The vulnerability underscores the critical importance of secure coding practices in XML processing components and the need for regular security assessments of third-party libraries and components that handle user-supplied data.