CVE-2023-20959
📋 TL;DR
This vulnerability allows guest users on Android 13 devices to escalate privileges locally by accessing the AddSupervisedUserActivity without proper permission checks. Attackers could gain elevated privileges without user interaction. Only Android 13 devices are affected.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Guest user gains administrative control over the device, potentially accessing sensitive data, installing malware, or modifying system settings.
Likely Case
Guest user gains access to restricted functions or user data they shouldn't have permission to access.
If Mitigated
Proper permission checks prevent guest users from accessing the supervised user activity, maintaining normal security boundaries.
🎯 Exploit Status
Exploitation requires guest user access but no additional privileges. No user interaction needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Update March 2023 or later
Vendor Advisory: https://source.android.com/security/bulletin/2023-03-01
Restart Required: Yes
Instructions:
1. Go to Settings > System > System Update. 2. Check for and install the March 2023 Android security update. 3. Restart the device after installation completes.
🔧 Temporary Workarounds
Disable Guest User Mode
androidPrevent exploitation by disabling guest user functionality on the device
Settings > System > Multiple users > Guest > Turn off
🧯 If You Can't Patch
- Disable guest user mode on all Android 13 devices
- Restrict physical access to devices and implement device management policies
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If it shows Android 13 without March 2023 security patch, device is vulnerable.Check Version:
adb shell getprop ro.build.version.releaseVerify Fix Applied:
Verify Android version is 13 with March 2023 or later security patch in Settings > About phone > Android version.📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to AddSupervisedUserActivity
- Guest user performing privileged operations
Network Indicators:
- None - this is a local exploit
SIEM Query:
Look for guest user activity logs showing access to supervised user functions