CVE-2023-21021
📋 TL;DR
This Android vulnerability allows a guest user account to change network settings of an admin user due to a missing permission check in the WiFi service. This could lead to local privilege escalation without requiring user interaction. It affects Android 13 devices with guest user functionality enabled.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Guest user gains administrative control over network settings, potentially enabling further attacks like network interception, device isolation, or facilitating other privilege escalation vectors.
Likely Case
Guest user modifies WiFi configurations, disconnects devices from networks, or changes proxy settings, disrupting network connectivity for admin users.
If Mitigated
With proper patching, guest users are restricted to their intended permissions and cannot modify admin network settings.
🎯 Exploit Status
Exploitation requires local access via a guest user account but no additional privileges or user interaction.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android security patch level 2023-03-01 or later
Vendor Advisory: https://source.android.com/security/bulletin/pixel/2023-03-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > System update. 2. Install the March 2023 security patch or later. 3. Reboot the device after installation.
🔧 Temporary Workarounds
Disable Guest User
androidRemove the guest user account functionality to prevent exploitation.
Settings > System > Multiple users > Guest > Remove guest
🧯 If You Can't Patch
- Disable guest user accounts on all affected Android devices.
- Monitor for unusual network configuration changes or guest user activity in system logs.
🔍 How to Verify
Check if Vulnerable:
Check Android version and security patch level in Settings > About phone > Android version and Security update level. If Android 13 with patch level earlier than 2023-03-01, device is vulnerable.Check Version:
adb shell getprop ro.build.version.release && adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Confirm security patch level is 2023-03-01 or later in Settings > About phone > Security update level.📡 Detection & Monitoring
Log Indicators:
- Unusual WiFi configuration changes initiated by guest user accounts in system logs (logcat).
- Permission denial errors related to WifiServiceImpl in Android system logs.
Network Indicators:
- Sudden changes to WiFi network settings or connectivity issues on devices with guest users active.
SIEM Query:
source="android_system" AND (event="wifi_config_change" AND user="guest") OR (message="*WifiServiceImpl*" AND message="*permission*denied*")