CVE-2023-21390
📋 TL;DR
CVE-2023-21390 is a permission bypass vulnerability in Android's SIM component that allows attackers to evade mobile preference restrictions without user interaction. This leads to local privilege escalation, potentially giving attackers elevated access to device functions. All Android devices running vulnerable versions are affected.
💻 Affected Systems
- Android OS
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to bypass all SIM-based security controls, access sensitive mobile network functions, and potentially intercept communications.
Likely Case
Limited privilege escalation allowing unauthorized access to SIM-related functions and mobile preferences that should be restricted.
If Mitigated
No impact if patched; otherwise, risk depends on device configuration and existing security controls.
🎯 Exploit Status
Exploitation requires local access but no user interaction; likely requires malicious app installation or physical access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android 14 and security updates for earlier versions
Vendor Advisory: https://source.android.com/docs/security/bulletin/android-14
Restart Required: Yes
Instructions:
1. Update Android device to Android 14 or latest security patch. 2. Check for system updates in Settings > System > System update. 3. Install available updates and restart device.
🔧 Temporary Workarounds
Restrict app installations
androidPrevent installation of untrusted apps that could exploit this vulnerability
Enable Google Play Protect
androidUse built-in malware scanning to detect potentially malicious apps
🧯 If You Can't Patch
- Isolate affected devices from sensitive networks and data
- Implement strict app installation policies and monitor for suspicious behavior
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If version is below Android 14, device may be vulnerable.Check Version:
adb shell getprop ro.build.version.releaseVerify Fix Applied:
Verify Android version is 14 or higher, or check that latest security patch is installed in Settings > Security & privacy > Security update.📡 Detection & Monitoring
Log Indicators:
- Unusual SIM-related permission requests
- Unexpected mobile preference changes
- Suspicious app behavior with SIM access
Network Indicators:
- Unusual mobile network activity from compromised devices
SIEM Query:
source="android_logs" AND (event="SIM_PERMISSION_BYPASS" OR event="MOBILE_PREFERENCE_CHANGE")