CVE-2009-3985 in Firefox
Summary
by MITRE
Mozilla Firefox before 3.0.16 and 3.5.x before 3.5.6, and SeaMonkey before 2.0.1, allows remote attackers to associate spoofed content with an invalid URL by setting document.location to this URL, and then writing arbitrary web script or HTML to the associated blank document, a related issue to CVE-2009-2654.
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Analysis
by VulDB Data Team • 08/30/2021
This vulnerability exists in mozilla firefox versions prior to 3.0.16 and 3.5.x versions prior to 3.5.6, as well as seaMonkey versions before 2.0.1, representing a significant security flaw that enables remote attackers to manipulate url associations and content display. the issue stems from how the browser handles document.location assignments and subsequent content writing operations within blank documents, creating a pathway for malicious actors to spoof content while maintaining misleading url representations. the vulnerability operates by exploiting the browser's handling of url context when document.location is set to an invalid url, followed by writing arbitrary script or html content to the associated blank document. this behavior creates a discrepancy between the displayed content and the actual url context, allowing attackers to deceive users about the true source of web content.
the technical implementation of this vulnerability involves the manipulation of the document object model and browser security mechanisms that typically enforce url integrity and content association. when an attacker sets document.location to an invalid url, the browser creates a blank document context that should theoretically maintain proper url association, but the subsequent ability to write arbitrary content to this document allows for the injection of malicious scripts or misleading html. this flaw represents a cross-site scripting vulnerability that leverages the browser's document handling mechanisms to create a false security context where content appears to originate from one source while actually being generated from another. the vulnerability is classified under cwe-79 as a cross-site scripting issue and aligns with attack techniques described in the attack tree framework where adversaries exploit browser inconsistencies to manipulate user perception of web content authenticity.
the operational impact of this vulnerability is substantial as it enables attackers to create convincing spoofing scenarios that can deceive users into believing they are interacting with legitimate websites while actually executing malicious code or displaying fraudulent content. users may be tricked into entering sensitive information on spoofed pages or may unknowingly execute harmful scripts that appear to originate from trusted domains. the attack vector allows for sophisticated social engineering campaigns where the url displayed in the browser address bar may be legitimate while the actual content is malicious, making detection and prevention significantly more challenging for end users and security systems. this vulnerability particularly affects web browsing security by undermining the fundamental trust model that users place in url representations and browser security indicators.
mitigation strategies for this vulnerability require immediate patching of affected firefox and seamonkey versions to ensure proper document handling and url context management. users should maintain updated browser versions and enable security features such as content filtering and script blocking where available. organizations should implement comprehensive browser security policies that include regular updates and monitoring for vulnerable browser versions. the fix implemented by mozilla involved strengthening the document.location handling mechanisms to prevent the association of spoofed content with invalid urls, ensuring that when document.location is set to an invalid url, the browser maintains proper security context and prevents subsequent content injection. security teams should also consider implementing additional monitoring for suspicious url patterns and content delivery that may indicate exploitation attempts. this vulnerability highlights the importance of maintaining robust browser security mechanisms and the need for continuous security testing to identify and remediate inconsistencies in web browser implementations that could be exploited for malicious purposes.