CVE-2021-0318
📋 TL;DR
This vulnerability allows local attackers to escalate privileges on Android devices through an out-of-bounds write caused by a use-after-free bug in the sensor event handling code. It affects Android versions 8.1 through 11, requiring no user interaction for exploitation. Attackers could gain elevated system privileges without needing additional execution permissions.
💻 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-level privileges, potentially installing persistent malware or accessing sensitive data.
Likely Case
Local privilege escalation enabling attackers to bypass security controls, access protected system resources, or install malicious applications.
If Mitigated
Limited impact if devices are patched, isolated from untrusted users, or have additional security controls like SELinux enforcement.
🎯 Exploit Status
Exploitation requires local access but no user interaction. The use-after-free to out-of-bounds write chain requires specific memory manipulation knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin January 2021 patches
Vendor Advisory: https://source.android.com/security/bulletin/2021-01-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > Advanced > System update. 2. Install the January 2021 security patch or later. 3. Reboot the device after installation.
🔧 Temporary Workarounds
Disable unnecessary sensor permissions
androidRestrict sensor access to trusted applications only to reduce attack surface
adb shell pm revoke <package_name> android.permission.BODY_SENSORS
adb shell pm revoke <package_name> android.permission.ACTIVITY_RECOGNITION
🧯 If You Can't Patch
- Isolate affected devices from untrusted users and limit physical access
- Implement application allowlisting to prevent untrusted apps from running
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level: Settings > About phone > Android security patch level. If before January 2021, device is vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify Android security patch level shows January 2021 or later date.📡 Detection & Monitoring
Log Indicators:
- Unusual sensor access patterns
- Process privilege escalation attempts
- Kernel panic or crash logs related to sensor services
Network Indicators:
- None - this is a local exploit
SIEM Query:
source="android_logs" AND (event="privilege_escalation" OR process="system_server" AND error="use-after-free")