CVE-2023-37455 in Firefox
Summary
by MITRE • 07/12/2023
The permission request prompt from the site in the background tab was overlaid on top of the site in the foreground tab. This vulnerability affects Firefox for iOS < 115.
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Analysis
by VulDB Data Team • 08/02/2023
This vulnerability represents a critical cross-tab security issue that undermines the fundamental isolation principles of web browser tab management. The flaw allows malicious websites to exploit the permission request prompt mechanism by overlaying it on top of content in the foreground tab while the user interacts with a background tab. This creates a dangerous scenario where users may unknowingly grant permissions to malicious sites through deceptive overlay techniques that appear legitimate but are actually designed to manipulate user interaction. The vulnerability specifically targets Firefox for iOS versions prior to 115, indicating a mobile-specific implementation weakness in the browser's tab management and overlay handling systems. This issue directly violates the security principle of tab isolation, where each tab should maintain its own distinct security context without interference from other tabs.
The technical implementation flaw stems from improper handling of permission prompts across tab boundaries, where the browser fails to properly validate which tab should be receiving user interaction for permission requests. This creates an overlay attack vector where a background tab's permission prompt can visually obscure or interfere with the foreground tab's content, potentially tricking users into granting unwanted permissions. The vulnerability operates at the user interface level rather than at the core security architecture, making it particularly insidious because it exploits the natural user behavior of switching between tabs without considering the security implications of background tab interactions. This flaw can be categorized under CWE-691 as an insufficient control of a resource through multiple interfaces, specifically in the context of browser tab management and permission handling.
The operational impact of this vulnerability extends beyond simple permission manipulation to potentially enable more sophisticated attacks such as credential theft, data exfiltration, or malicious software installation. Users may be tricked into granting permissions for microphone, camera, location services, or file access through deceptive overlays that appear to be legitimate prompts from the currently active tab. Attackers could leverage this vulnerability to create convincing phishing scenarios where malicious sites overlay permission requests on top of trusted websites, exploiting the trust users place in their active browsing session. The mobile environment exacerbates this risk as iOS users often switch between apps and tabs frequently, increasing the likelihood of encountering such overlay attacks. This vulnerability aligns with ATT&CK technique T1556.004 for credential access through deceptive prompts and can be classified as a form of UI redressing or overlay attack that bypasses normal browser security boundaries.
Mitigation strategies should focus on implementing proper tab isolation mechanisms that prevent background tab permission prompts from interfering with foreground tab content. Browser vendors should enforce strict validation of which tab can legitimately receive user interaction for permission requests and implement overlay restrictions that maintain clear visual separation between tabs. Users should be advised to update to Firefox for iOS version 115 or later where this vulnerability has been patched, and to exercise heightened caution when encountering permission prompts, particularly when switching between tabs or applications. Security best practices recommend that users verify the authenticity of permission requests through multiple means and avoid granting sensitive permissions to unfamiliar sites. Additionally, browser security teams should implement automated monitoring for cross-tab interference patterns and establish clear protocols for handling permission prompts that maintain user control over security decisions. The vulnerability underscores the importance of maintaining strict separation between browser tabs and implementing robust security boundaries that prevent malicious interference between different browsing contexts.