CVE-2021-39662
📋 TL;DR
This vulnerability in Android's MediaProvider allows local attackers to access media collections without proper permission checks. It enables local privilege escalation on Android 11 and 12 devices. Exploitation requires user execution privileges but no user interaction.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains unauthorized access to all media content (photos, videos, documents) stored by the media provider, potentially including sensitive personal or corporate data.
Likely Case
Malicious app accesses media files it shouldn't have permission to view, compromising user privacy and potentially exfiltrating sensitive content.
If Mitigated
Proper app sandboxing and security updates prevent exploitation, limiting access to authorized apps only.
🎯 Exploit Status
Requires developing or modifying an Android app to exploit the missing permission check in MediaProvider.java.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin May 2022 patches
Vendor Advisory: https://source.android.com/security/bulletin/2022-05-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > System update. 2. Install the May 2022 security patch or later. 3. Reboot device after installation.
🔧 Temporary Workarounds
Restrict app installations
androidOnly install apps from trusted sources like Google Play Store and avoid sideloading unknown apps.
Review app permissions
androidRegularly review and restrict media access permissions for installed apps in Settings > Apps > [App Name] > Permissions.
🧯 If You Can't Patch
- Implement Mobile Device Management (MDM) to control app installations and enforce security policies
- Use app sandboxing solutions and regularly audit installed applications for suspicious behavior
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If version is 11 or 12 without May 2022 security patch, device is vulnerable.Check Version:
adb shell getprop ro.build.version.releaseVerify Fix Applied:
Verify Android version is updated beyond May 2022 security patch level in Settings > About phone > Android security update.📡 Detection & Monitoring
Log Indicators:
- Unusual media access patterns from apps, particularly accessing media collections without proper permissions
Network Indicators:
- Unusual data exfiltration from media-related apps
SIEM Query:
Look for Android security events indicating privilege escalation attempts or unauthorized media access