CVE-2021-0437
📋 TL;DR
This CVE describes a double-free vulnerability in Android's DRM plugin that could allow local privilege escalation. Attackers could exploit this to gain elevated privileges on affected Android devices without user interaction. The vulnerability affects Android versions 8.1 through 11.
💻 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
Complete device compromise allowing attackers to execute arbitrary code with system privileges, potentially leading to data theft, surveillance, or persistent malware installation.
Likely Case
Local privilege escalation allowing attackers to bypass security restrictions, access sensitive data, or install malicious applications with elevated permissions.
If Mitigated
Limited impact if devices are patched or have security controls preventing local code execution; standard user data remains protected by Android's sandboxing.
🎯 Exploit Status
Exploitation requires local access and understanding of Android's DRM subsystem; no public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Patch Level 2021-04-01 or later
Vendor Advisory: https://source.android.com/security/bulletin/2021-04-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > Advanced > System update. 2. Install the April 2021 security patch or later. 3. Reboot the device after installation.
🔧 Temporary Workarounds
Disable unnecessary DRM services
androidReduce attack surface by disabling unused DRM-related services if not required for device functionality.
adb shell pm disable-user --user 0 com.android.drm
🧯 If You Can't Patch
- Restrict physical access to devices and implement application allowlisting to prevent malicious app installation.
- Use mobile device management (MDM) solutions to enforce security policies and monitor for suspicious activity.
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level in Settings > About phone > Android version > Security patch level. If date is before April 2021, device is vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level shows April 2021 or later after applying updates.📡 Detection & Monitoring
Log Indicators:
- Unusual DRM service crashes or privilege escalation attempts in system logs
- Suspicious process creation with elevated privileges
Network Indicators:
- Not applicable - local vulnerability
SIEM Query:
Not applicable for typical SIEM monitoring of this local vulnerability