CVE-2020-6828
📋 TL;DR
This vulnerability allows a malicious Android app to craft an Intent that Firefox for Android processes, potentially overwriting files in the user's profile directory. By controlling arbitrary preferences through a crafted user.js file, an attacker could achieve effects equivalent to arbitrary code execution. Only Firefox for Android users running affected versions are impacted.
💻 Affected Systems
- Firefox for Android
📦 What is this software?
Firefox Esr by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of Firefox for Android through arbitrary code execution, allowing data theft, credential harvesting, and further device compromise.
Likely Case
Malicious preference injection leading to browser hijacking, data exfiltration, or installation of additional malware.
If Mitigated
No impact if Firefox is updated or if malicious apps are prevented from installing.
🎯 Exploit Status
Exploitation requires a malicious Android app to be installed and to craft a specific Intent targeting Firefox.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox ESR 68.7 or later
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2020-13/
Restart Required: Yes
Instructions:
1. Open Firefox for Android. 2. Go to Settings > About Firefox. 3. Allow automatic update or manually update to version 68.7 or higher from Google Play Store.
🔧 Temporary Workarounds
Disable Firefox for Android
androidTemporarily disable or uninstall Firefox for Android until patched.
Settings > Apps > Firefox > Disable/Uninstall
Restrict app installations
androidPrevent installation of unknown Android apps that could exploit this vulnerability.
Settings > Security > Unknown sources (disable)
🧯 If You Can't Patch
- Use alternative browsers on Android devices.
- Implement mobile device management (MDM) to block malicious app installations.
🔍 How to Verify
Check if Vulnerable:
Check Firefox version in Settings > About Firefox. If version is less than 68.7, it is vulnerable.Check Version:
Not applicable for Android GUI; use Settings > About Firefox.Verify Fix Applied:
Confirm Firefox version is 68.7 or higher in Settings > About Firefox.📡 Detection & Monitoring
Log Indicators:
- Unusual Intent activities targeting Firefox from other apps in Android logs.
Network Indicators:
- None specific to this vulnerability.
SIEM Query:
Not typically applicable for mobile app vulnerabilities.