CVE-2011-2366 in Thunderbird
Summary
by MITRE
Mozilla Gecko before 5.0, as used in Firefox before 5.0 and Thunderbird before 5.0, does not block use of a cross-domain image as a WebGL texture, which allows remote attackers to obtain approximate copies of arbitrary images via a timing attack involving a crafted WebGL fragment shader.
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Analysis
by VulDB Data Team • 11/13/2021
This vulnerability resides in the Mozilla Gecko rendering engine that powers Firefox and Thunderbird browsers prior to version 5.0. The flaw represents a significant security weakness in the WebGL implementation that enables cross-domain information leakage through sophisticated timing attacks. The vulnerability specifically affects the handling of image textures in WebGL contexts where cross-domain images are permitted to be used as texture sources without proper security restrictions.
The technical implementation flaw occurs when WebGL fragment shaders process cross-domain images as textures, creating a scenario where remote attackers can infer information about the source images through timing variations in shader execution. This timing-based approach exploits the differences in processing time required for various image data patterns, allowing attackers to reconstruct approximate copies of arbitrary images. The vulnerability stems from insufficient sandboxing and access controls within the WebGL texture handling mechanism that should have prevented cross-domain image usage as textures.
The operational impact of this vulnerability is substantial as it enables attackers to perform sophisticated reconnaissance attacks against users of affected browsers. Through carefully crafted WebGL fragment shaders, adversaries can gather approximate copies of images from different domains, potentially including sensitive visual data, user interface elements, or even personal photographs. This capability extends beyond simple information disclosure to enable more advanced attacks where visual information can be used to infer user activities, preferences, or even personal details. The vulnerability affects not just web applications but also email clients like Thunderbird that utilize the same Gecko engine, expanding the potential attack surface significantly.
Mitigation strategies for this vulnerability require immediate browser updates to versions 5.0 or later where the security restrictions have been properly implemented. Organizations should ensure all users are running patched versions of Firefox and Thunderbird to prevent exploitation. Additionally, administrators should consider implementing network-level protections such as content filtering and web application firewalls that can detect and block suspicious WebGL activity. The vulnerability aligns with CWE-200, which addresses information exposure, and maps to ATT&CK technique T1056.001 for input validation and T1566 for credential access through social engineering. Network monitoring should be enhanced to detect unusual WebGL shader execution patterns that may indicate exploitation attempts, as this type of attack requires careful crafting of malicious shaders to achieve the timing-based information leakage.