CVE-2021-39732
📋 TL;DR
This CVE describes an integer overflow vulnerability in the Android kernel's lwis_ioctl.c file that allows local privilege escalation. An attacker could exploit this to gain root access on affected Android devices without requiring user interaction. This affects Android devices running vulnerable kernel versions.
💻 Affected Systems
- Android devices with vulnerable kernel
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root privileges, allowing installation of persistent malware, data theft, and bypassing all security controls.
Likely Case
Local privilege escalation enabling attackers to bypass app sandboxing, access sensitive data, and install malicious apps with elevated permissions.
If Mitigated
Limited impact if devices are patched, have SELinux enforcing mode, and app sandboxing prevents lateral movement.
🎯 Exploit Status
Requires local access to device. No user interaction needed but attacker needs ability to execute code on device.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: March 2022 Android security patch level or later
Vendor Advisory: https://source.android.com/security/bulletin/pixel/2022-03-01
Restart Required: Yes
Instructions:
1. Check for system updates in Settings > System > System update. 2. Install March 2022 or later security patch. 3. Reboot device after installation.
🔧 Temporary Workarounds
Restrict local code execution
androidPrevent installation of untrusted apps and limit developer/debugging options
🧯 If You Can't Patch
- Isolate vulnerable devices from sensitive networks and data
- Implement strict app whitelisting and disable USB debugging
🔍 How to Verify
Check if Vulnerable:
Check Android security patch level in Settings > About phone > Android version. If before March 2022, device is vulnerable.Check Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level shows March 2022 or later in Settings > About phone > Android version.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- SELinux denials for privileged operations
- Unexpected root access attempts
Network Indicators:
- Unusual outbound connections from device after local compromise
SIEM Query:
source="android-kernel" AND ("lwis_ioctl" OR "integer overflow" OR "out of bounds write")