CVE-2024-4776
📋 TL;DR
A vulnerability in Firefox allows a file dialog displayed during full-screen mode to leave the window disabled, potentially enabling clickjacking attacks. This affects Firefox versions before 126. Users running vulnerable versions are at risk.
💻 Affected Systems
- Mozilla Firefox
📦 What is this software?
Firefox by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Attackers could overlay malicious content over the disabled window, tricking users into clicking on unintended elements, potentially leading to credential theft or malware installation.
Likely Case
Clickjacking attacks where users inadvertently interact with hidden malicious elements, possibly resulting in unintended actions like downloading files or visiting malicious sites.
If Mitigated
With proper controls like updated browsers and user awareness, impact is limited to minor UI disruption without significant security compromise.
🎯 Exploit Status
Exploitation requires user interaction (triggering file dialog in full-screen mode) but is technically simple once conditions are met.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 126
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2024-21/
Restart Required: Yes
Instructions:
1. Open Firefox. 2. Click menu > Help > About Firefox. 3. Allow Firefox to check for and install updates. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Avoid Full-Screen Mode
allPrevent triggering the vulnerability by not using full-screen mode in Firefox.
Disable Automatic File Dialog
allConfigure Firefox to not automatically show file dialogs in certain contexts.
🧯 If You Can't Patch
- Use alternative browsers for full-screen activities
- Implement network filtering to block malicious sites that might exploit this
🔍 How to Verify
Check if Vulnerable:
Check Firefox version: if version is less than 126, the system is vulnerable.Check Version:
firefox --versionVerify Fix Applied:
Confirm Firefox version is 126 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Unusual full-screen mode entries in browser logs
- Multiple file dialog errors
Network Indicators:
- Traffic to known malicious sites coinciding with full-screen browser sessions
SIEM Query:
source="firefox.log" AND "full-screen" AND "dialog"