CVE-2016-2831 in Firefox
Summary
by MITRE
Mozilla Firefox before 47.0 and Firefox ESR 45.x before 45.2 do not ensure that the user approves the fullscreen and pointerlock settings, which allows remote attackers to cause a denial of service (UI outage), or conduct clickjacking or spoofing attacks, via a crafted web site.
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Analysis
by VulDB Data Team • 10/23/2024
This vulnerability in Mozilla Firefox affects versions prior to 47.0 and Firefox ESR 45.x prior to 45.2, representing a critical flaw in the browser's user interface security mechanisms. The issue stems from insufficient user consent validation for fullscreen and pointerlock functionalities, creating a significant attack surface that adversaries can exploit to manipulate user interactions and system behavior. The vulnerability is classified under CWE-613, which addresses insufficient session validation, and aligns with ATT&CK technique T1059.001 for user execution through malicious web content. The flaw allows attackers to bypass normal user approval processes that should occur when websites request these powerful browser capabilities.
The technical implementation of this vulnerability involves the browser's failure to properly enforce user consent before granting fullscreen or pointerlock permissions to web pages. When users visit malicious websites, the exploit can trigger these modes without proper user interaction, leading to a range of security implications. The absence of proper validation mechanisms means that websites can programmatically activate these features, potentially causing the browser interface to become unresponsive or rendering the user unable to interact with their browser normally. This creates a persistent UI outage that can last until the user manually resets their browser state or restarts the application.
The operational impact of this vulnerability extends beyond simple denial of service conditions to include sophisticated attack vectors such as clickjacking and spoofing operations. Attackers can leverage the bypassed consent mechanisms to create deceptive user experiences where malicious sites appear to take control of the browser interface while users believe they are interacting with legitimate content. This manipulation allows for the execution of phishing attacks, credential theft operations, and other malicious activities that rely on user interface deception. The vulnerability essentially undermines the browser's security model by removing the user's ability to control critical interface behaviors that could compromise their security posture.
Organizations and users should immediately update to Firefox versions 47.0 or later for regular releases, or Firefox ESR 45.2 or later for extended support releases to remediate this vulnerability. Security teams should implement network monitoring to detect suspicious web traffic patterns that might indicate exploitation attempts, particularly around fullscreen and pointerlock API usage. Browser security policies should include restrictions on these APIs for untrusted domains, and users should be educated about the importance of verifying website permissions before granting fullscreen or pointerlock access. The vulnerability demonstrates the critical importance of user consent validation in browser security models and highlights the need for comprehensive permission management systems that prevent unauthorized interface manipulation.