CVE-2024-5689 in Firefox
Summary
by MITRE • 06/11/2024
In addition to detecting when a user was taking a screenshot (XXX), a website was able to overlay the 'My Shots' button that appeared, and direct the user to a replica Firefox Screenshots page that could be used for phishing. This vulnerability affects Firefox < 127.
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Analysis
by VulDB Data Team • 08/17/2025
This vulnerability represents a sophisticated cross-site scripting and user interface deception attack that exploits Firefox's screenshot detection mechanism to facilitate phishing operations. The flaw allows malicious websites to intercept screenshot events and overlay deceptive UI elements that appear to be legitimate Firefox functionality. Specifically when users attempt to take screenshots, the malicious site can detect this action and immediately display a counterfeit 'My Shots' button that mimics the genuine Firefox Screenshots interface. This overlay technique creates an environment where users are deceived into believing they are interacting with legitimate browser functionality while actually being directed to a phishing replica page. The vulnerability specifically targets Firefox versions prior to 127, indicating a regression or implementation flaw in the browser's security model that fails to properly isolate legitimate screenshot detection from malicious UI overlay attempts.
The technical implementation of this vulnerability stems from insufficient sandboxing and UI isolation mechanisms within Firefox's screenshot handling system. When a user initiates a screenshot, the browser's detection mechanism should only trigger within the legitimate context of the screenshot feature itself. However, the flaw allows third-party websites to intercept these events and subsequently overlay their own UI elements that leverage the same visual patterns and user interface elements as the genuine Firefox Screenshots functionality. This creates an attack surface where the malicious website can leverage the browser's legitimate screenshot detection to establish a false sense of trust and security. The underlying mechanism likely involves event listener registration and DOM manipulation that occurs during screenshot detection, allowing the malicious site to inject content that appears to be part of the browser's native functionality.
The operational impact of this vulnerability extends beyond simple phishing attacks to represent a significant threat to user security awareness and browser trust models. Users who are unaware of the deception may inadvertently provide sensitive information to the phishing replica page, believing they are interacting with legitimate Firefox functionality. The attack vector is particularly insidious because it leverages the user's own actions to create the deception, making it more difficult to detect than traditional phishing techniques. The vulnerability essentially transforms the browser's legitimate security feature into an attack vector, undermining user confidence in the browser's ability to protect them from malicious websites. This creates a scenario where users may be more likely to trust other phishing attempts that exploit similar UI deception techniques, as they have already been deceived by this legitimate-looking browser feature.
The vulnerability aligns with several cybersecurity frameworks and attack patterns including CWE-79 which addresses cross-site scripting vulnerabilities, and relates to ATT&CK technique T1566 which covers social engineering through phishing. Organizations and users should immediately upgrade to Firefox version 127 or later to remediate this vulnerability. Additionally, browser vendors should implement stricter isolation between legitimate screenshot detection and third-party UI manipulation capabilities. Security measures should include enhanced sandboxing of screenshot functionality, stricter content security policies for overlay elements, and user awareness training about recognizing UI deception techniques. Network administrators should monitor for suspicious websites that may attempt to exploit this vulnerability and consider implementing browser security policies that limit third-party UI manipulation capabilities. The remediation process should also include verification that the updated browser version properly isolates screenshot detection events from UI overlay capabilities to prevent similar vulnerabilities from emerging in future releases.