CVE-2007-2870 in Firefox
Summary
by MITRE
Mozilla Firefox 1.5.x before 1.5.0.12 and 2.x before 2.0.0.4, and SeaMonkey 1.0.9 and 1.1.2, allows remote attackers to bypass the same-origin policy and conduct cross-site scripting (XSS) and other attacks by using the addEventListener method to add an event listener for a site, which is executed in the context of that site.
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Analysis
by VulDB Data Team • 07/20/2019
This vulnerability represents a critical security flaw in Mozilla Firefox and SeaMonkey browsers that undermines fundamental web security mechanisms. The issue stems from improper handling of the addEventListener method within the browser's JavaScript engine, allowing malicious actors to circumvent the same-origin policy that normally prevents scripts from one domain from accessing resources on another domain. The vulnerability affects specific versions of Firefox 1.5.x and 2.x series, as well as SeaMonkey 1.0.9 and 1.1.2 releases, creating a significant attack surface for remote code execution and data theft. The flaw enables attackers to inject malicious code that executes in the context of targeted websites, effectively breaking down the browser's security boundaries.
The technical implementation of this vulnerability exploits the event listener registration mechanism to create a scenario where JavaScript code can be executed with elevated privileges. When an attacker uses the addEventListener method to register handlers for specific events on foreign domains, the browser's security model fails to properly validate the execution context, allowing the malicious code to run within the target site's security context. This creates a pathway for cross-site scripting attacks where the attacker's code can access sensitive data, manipulate DOM elements, and potentially exfiltrate information from authenticated sessions. The vulnerability is particularly dangerous because it operates at the core browser functionality level, making it difficult to detect and prevent through standard security measures.
The operational impact of this vulnerability extends far beyond simple XSS attacks, as it provides attackers with the ability to perform sophisticated web-based assaults that can compromise user sessions and steal confidential information. Users browsing compromised websites become vulnerable to session hijacking, credential theft, and data manipulation attacks that can persist across multiple browsing sessions. The vulnerability enables attackers to execute code in the context of legitimate websites, making it extremely difficult for users and security systems to distinguish between benign and malicious activity. This creates a persistent threat vector that can be exploited across multiple applications and services that rely on the affected browser versions for web access.
Security mitigations for this vulnerability require immediate patching of affected browser versions to ensure proper enforcement of same-origin policies and secure handling of event listeners. Organizations should implement comprehensive browser update policies and ensure all users maintain current versions of their web browsers. Additional protective measures include deploying web application firewalls, implementing content security policies, and utilizing browser security extensions that can detect and block suspicious event listener registrations. The vulnerability aligns with CWE-94, which addresses the improper control of generation of code, and maps to ATT&CK technique T1059.007 for scripting, demonstrating how the flaw enables attackers to execute malicious scripts in targeted contexts. Regular security audits and penetration testing should verify that browser security configurations properly enforce cross-origin restrictions and prevent unauthorized code execution in sensitive contexts.