CVE-2012-3994 in Firefox
Summary
by MITRE
Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbird before 16.0, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 allow remote attackers to conduct cross-site scripting (XSS) attacks via a binary plugin that uses Object.defineProperty to shadow the top object, and leverages the relationship between top.location and the location property.
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Analysis
by VulDB Data Team • 10/22/2024
This vulnerability affects multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey versions prior to their respective secure releases. The flaw resides in how these applications handle binary plugins and their interaction with JavaScript objects, specifically exploiting the Object.defineProperty method to manipulate the top object context. The vulnerability stems from insufficient sanitization of plugin content that allows malicious actors to inject crafted JavaScript code through binary plugins, creating a path for cross-site scripting attacks that can compromise user sessions and data integrity.
The technical mechanism involves binary plugins utilizing Object.defineProperty to shadow or override the top object properties, particularly leveraging the relationship between top.location and the location property. This exploitation technique allows attackers to manipulate the browser's execution context by hijacking the top object reference, which typically points to the highest-level window object in the browser's hierarchy. When the plugin executes, it can effectively redirect or modify the behavior of the top object, creating opportunities for malicious code execution that bypasses normal security boundaries and access controls.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it enables attackers to perform session hijacking, data theft, and potentially full browser compromise. The vulnerability is particularly dangerous because it operates at the plugin level where security boundaries are typically less strict than regular web content. Attackers can craft malicious binary plugins that appear legitimate to the browser's security model, allowing them to execute arbitrary code in the context of the user's browsing session. This creates a significant risk for enterprise environments where users may encounter compromised plugins through various attack vectors including malicious websites, email attachments, or compromised software distributions.
Mitigation strategies should focus on immediate patching of affected versions to the secure releases mentioned in the vulnerability description. Organizations should implement strict plugin management policies that disable or restrict binary plugin execution, particularly for untrusted sources. Browser hardening measures including disabling unnecessary plugin support, implementing content security policies, and utilizing sandboxing technologies can provide additional defense layers. Security teams should monitor for indicators of compromise related to malicious plugin installations and implement web application firewalls to detect and block suspicious plugin-related traffic. This vulnerability aligns with CWE-79 Cross-site Scripting and follows ATT&CK technique T1059 Command and Scripting Interpreter, specifically focusing on JavaScript-based exploitation methods that leverage browser object manipulation. The vulnerability demonstrates the critical importance of proper plugin security boundaries and the need for comprehensive input validation across all browser components including plugin interfaces.