CVE-2002-0243 in Web Browser
Summary
by MITRE
Cross-site scripting vulnerability in Opera 6.0 and earlier allows remote attackers to execute arbitrary script via an Extended HTML Form, whose output from the remote server is not properly cleansed.
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Analysis
by VulDB Data Team • 04/12/2019
This cross-site scripting vulnerability exists in Opera 6.0 and earlier versions due to inadequate input sanitization when processing Extended HTML Form data. The flaw occurs when the browser receives output from remote servers that contains malicious script code within Extended HTML Form elements, which are not properly cleansed before rendering. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically representing a weakness in input validation where user-controllable data is directly incorporated into web page content without proper sanitization. The vulnerability enables attackers to inject malicious scripts that execute in the context of the victim's browser session, potentially allowing for session hijacking, data theft, or unauthorized actions on behalf of the user.
The technical implementation of this vulnerability stems from Opera's insufficient filtering mechanisms for Extended HTML Form elements that are processed server-side. When the browser encounters form data containing script tags or executable code within Extended HTML Form fields, it fails to properly sanitize this content before displaying it to the user. This processing gap allows attackers to craft malicious payloads that exploit the browser's trust in server-provided content. The vulnerability is particularly dangerous because Extended HTML Forms are designed to handle complex data structures and may contain various data types that are not properly validated or escaped during the rendering process. Attackers can leverage this weakness by crafting specially formatted form submissions that include malicious JavaScript code, which then executes when the page is rendered in the vulnerable browser.
The operational impact of this vulnerability extends beyond simple script execution to encompass significant security risks for users of affected Opera versions. When exploited, the vulnerability can facilitate session fixation attacks, where attackers steal user authentication tokens and gain unauthorized access to web applications. Additionally, the malicious scripts can perform actions such as modifying user data, redirecting to malicious sites, or harvesting sensitive information from the user's browsing session. The attack surface is broad as any web application that accepts Extended HTML Form data from untrusted sources and displays it within Opera 6.0 or earlier browsers becomes a potential target. This vulnerability particularly affects web applications that process user-generated content or integrate with external services that might return untrusted form data, making it a critical concern for organizations relying on older Opera browser versions.
The recommended mitigations for this vulnerability include immediate upgrade to Opera 7.0 or later versions where the input sanitization has been improved. Organizations should implement comprehensive input validation and output encoding for all user-controllable data, particularly when handling Extended HTML Form elements. Web application developers should employ proper content security policies and implement strict sanitization routines for all server-side form processing. The vulnerability demonstrates the importance of adhering to secure coding practices as outlined in the OWASP Top Ten and the MITRE ATT&CK framework's web application attack patterns. Organizations should also consider implementing web application firewalls and additional security layers to protect against such attacks while transitioning to more secure browser versions. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other browser components or web applications that might be susceptible to cross-site scripting attacks.