CVE-2021-0491
📋 TL;DR
CVE-2021-0491 is a local privilege escalation vulnerability in Android's memory management driver where a missing permission check allows attackers to gain elevated privileges without user interaction. This affects Android devices with specific System-on-Chip (SoC) implementations. The vulnerability enables attackers with local access to escalate from limited user privileges to kernel-level access.
💻 Affected Systems
- Android devices with specific System-on-Chip implementations
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, access all user data, bypass security controls, and potentially brick the device.
Likely Case
Local attacker gains root privileges to install malicious apps, steal sensitive data, or disable security features on affected Android devices.
If Mitigated
With proper patching, the vulnerability is eliminated; with proper app sandboxing and SELinux policies, exploitation attempts would be blocked or detected.
🎯 Exploit Status
Exploitation requires local access but no user interaction. Public exploit code exists, making weaponization likely for sophisticated attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin May 2021 patches
Vendor Advisory: https://source.android.com/security/bulletin/2021-05-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > System update. 2. Install May 2021 security patch or later. 3. Restart device. 4. For enterprise devices, push updates via MDM/EMM solutions.
🔧 Temporary Workarounds
Restrict app installations
androidOnly install apps from trusted sources (Google Play Store) and disable unknown sources installation
adb shell settings put secure install_non_market_apps 0
Enable Google Play Protect
androidEnsure Google Play Protect is active to detect and block malicious apps
Check Settings > Security > Google Play Protect
🧯 If You Can't Patch
- Isolate affected devices from sensitive networks and data
- Implement strict app whitelisting and monitor for suspicious privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level in Settings > About phone > Android version. If patch level is before May 2021, device is likely vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level shows May 2021 or later in Settings > About phone > Android version.📡 Detection & Monitoring
Log Indicators:
- Kernel logs showing unexpected memory management operations
- SELinux denials related to memory driver access
- Unexpected privilege escalation attempts in system logs
Network Indicators:
- Unusual outbound connections from system-level processes
- Command and control traffic from newly elevated processes
SIEM Query:
source="android_logs" AND (event_type="privilege_escalation" OR process_name="memory_driver_related")