CVE-2011-2986 in Firefox
Summary
by MITRE
Mozilla Firefox 4.x through 5, Thunderbird before 6, SeaMonkey 2.x before 2.3, and possibly other products, when the Direct2D (aka D2D) API is used on Windows, allows remote attackers to bypass the Same Origin Policy, and obtain sensitive image data from a different domain, by inserting this data into a canvas.
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Analysis
by VulDB Data Team • 11/18/2021
This vulnerability represents a critical security flaw in web browsers that utilize the Direct2D graphics API on Windows operating systems. The issue affects Mozilla Firefox versions 4.x through 5, Thunderbird versions prior to 6, and SeaMonkey versions 2.x prior to 2.3, creating a significant bypass of fundamental web security mechanisms. The vulnerability operates through a sophisticated exploitation of the canvas element's capabilities when Direct2D is enabled, allowing attackers to circumvent the same origin policy that normally prevents cross-domain data access.
The technical implementation of this vulnerability involves the manipulation of canvas rendering operations that utilize Direct2D acceleration. When the Direct2D API is active on Windows systems, it creates a pathway for attackers to access pixel data from images loaded from different domains. This occurs because the canvas element, which normally enforces strict cross-origin restrictions, fails to properly validate data access when Direct2D is engaged. The flaw essentially allows attackers to extract sensitive image data from other domains by leveraging the canvas element's ability to read pixel information from rendered images, effectively breaking the isolation guarantees that should exist between different web origins.
The operational impact of this vulnerability is substantial as it enables attackers to perform cross-domain data exfiltration without proper authorization. An attacker could potentially access sensitive images, user interface elements, or other visual data from different domains, which might contain confidential information or reveal application behavior patterns. This vulnerability particularly affects web applications that rely on visual data processing or that display content from multiple sources, as it undermines the fundamental security model that separates different origins. The attack vector is particularly concerning because it requires no user interaction beyond visiting a malicious website, making it a passive threat that can silently extract data from users' browsing sessions.
Security researchers have categorized this vulnerability under CWE-200, which addresses "Information Exposure," and it aligns with ATT&CK technique T1071.004 for application layer protocol usage. The flaw demonstrates how graphics acceleration APIs can introduce unexpected security boundaries, particularly when integrated with web rendering engines. Organizations should implement immediate mitigations including disabling Direct2D acceleration in affected browsers, updating to patched versions, and monitoring for suspicious canvas usage patterns in web applications. The vulnerability underscores the importance of comprehensive security testing for graphics APIs and highlights how seemingly benign features can create significant security risks when combined with web technologies. This issue serves as a reminder that modern browser security models must account for all execution paths, including those involving hardware acceleration features that may bypass traditional security controls.