CVE-2012-1965 in Firefox
Summary
by MITRE
Mozilla Firefox 4.x through 13.0 and Firefox ESR 10.x before 10.0.6 do not properly establish the security context of a feed: URL, which allows remote attackers to bypass unspecified cross-site scripting (XSS) protection mechanisms via a feed:javascript: URL.
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Analysis
by VulDB Data Team • 10/22/2024
The vulnerability described in CVE-2012-1965 represents a critical security flaw in Mozilla Firefox versions ranging from 4.x through 13.0 and Firefox ESR 10.x before 10.0.6. This issue stems from the browser's improper handling of feed: URLs, specifically when these URLs contain javascript: protocols. The flaw allows attackers to craft malicious feed:javascript: URLs that can bypass Firefox's built-in cross-site scripting protection mechanisms, creating a dangerous attack vector that could be exploited in various scenarios including phishing attacks and malicious content delivery.
The technical root cause of this vulnerability lies in Firefox's inadequate security context establishment for feed: URLs. When Firefox processes a feed: URL, it should properly validate and sanitize the content to prevent execution of embedded javascript code. However, the implementation failed to adequately distinguish between legitimate feed content and potentially malicious javascript payloads. This oversight creates a scenario where a feed:javascript: URL can be processed in a way that executes javascript code within the context of the feed reader rather than being properly restricted. The vulnerability specifically affects the browser's handling of feed protocols, which are designed to deliver syndicated content but are being misused to execute arbitrary code.
The operational impact of this vulnerability is significant as it allows remote attackers to bypass fundamental web security protections that are typically enforced by modern browsers. Attackers can craft malicious feed URLs that, when processed by vulnerable Firefox versions, could execute javascript code with the privileges of the feed reader interface. This creates opportunities for attackers to perform various malicious activities including credential theft, session hijacking, and delivery of additional malware. The vulnerability is particularly concerning because it operates at the protocol level, meaning that even if users are cautious about clicking links, they could still be compromised through legitimate-looking feed content that contains malicious javascript payloads.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws, and represents a specific instance where the security context is improperly established, allowing attackers to circumvent protection mechanisms. From an ATT&CK perspective, this vulnerability maps to techniques involving malicious content delivery and execution, specifically targeting the browser's content rendering and security enforcement capabilities. The attack surface is expanded by the fact that feed readers are often used to process content from untrusted sources, making this a particularly dangerous flaw in environments where users consume RSS feeds from multiple sources. Organizations should consider this vulnerability as part of their broader browser security posture, especially in environments where users may be exposed to untrusted feed content.
The primary mitigation strategy involves updating to patched versions of Firefox where this vulnerability has been addressed. Mozilla released updates for Firefox 10.0.6 and subsequent versions that properly establish the security context for feed: URLs, preventing the execution of javascript code within feed contexts. Additionally, users should be educated about the risks of consuming feed content from untrusted sources and should avoid clicking on suspicious feed links. Security administrators should also consider implementing network-level controls to filter feed content or block feed: URLs entirely if they are not required for business operations. The vulnerability serves as a reminder of the importance of proper protocol handling and security context establishment in web browsers, particularly for protocols that may be used to deliver content with varying trust levels.