CVE-2021-39626
📋 TL;DR
This vulnerability allows local attackers to bypass Bluetooth permission checks in Android's settings interface, potentially gaining elevated privileges without user interaction. It affects Android devices running versions 9 through 12, allowing attackers with physical access or malicious apps to exploit the confused deputy flaw.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
Android by Google
Android by Google
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains full control over Bluetooth settings and connected devices, potentially intercepting communications, pairing malicious devices, or accessing sensitive data transmitted via Bluetooth.
Likely Case
Local privilege escalation allowing unauthorized access to Bluetooth functionality, potentially enabling device pairing without user consent or accessing Bluetooth-connected peripherals.
If Mitigated
Limited impact with proper Android security updates and Bluetooth permission restrictions in place.
🎯 Exploit Status
Exploitation requires local access or malicious app installation. The confused deputy attack bypasses permission checks in ConnectedDeviceDashboardFragment.java.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin January 2022 patches
Vendor Advisory: https://source.android.com/security/bulletin/2022-01-01
Restart Required: Yes
Instructions:
1. Apply Android security updates from January 2022 or later. 2. Update to Android 12L or Android 13 if available. 3. Reboot device after update installation.
🔧 Temporary Workarounds
Disable Bluetooth when not in use
androidTurn off Bluetooth functionality to prevent exploitation through this vector
adb shell settings put global bluetooth_on 0
Settings > Connected devices > Connection preferences > Bluetooth > Turn off
Restrict Bluetooth permissions
androidReview and restrict Bluetooth permissions for installed applications
Settings > Apps > [App Name] > Permissions > Nearby devices > Deny
🧯 If You Can't Patch
- Implement strict physical security controls for Android devices
- Use mobile device management (MDM) solutions to restrict Bluetooth functionality
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If version is 9, 10, 11, or 12 without January 2022 security patches, device is vulnerable.Check Version:
adb shell getprop ro.build.version.release && adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify Android security patch level is January 2022 or later in Settings > About phone > Android security patch level.📡 Detection & Monitoring
Log Indicators:
- Unusual Bluetooth permission requests
- Bluetooth settings access by unauthorized processes
- Security exception logs related to ConnectedDeviceDashboardFragment
Network Indicators:
- Unexpected Bluetooth pairing attempts
- Unusual Bluetooth device connections
SIEM Query:
source="android_logs" AND ("ConnectedDeviceDashboardFragment" OR "A-194695497" OR "CVE-2021-39626")