CVE-2023-21092
📋 TL;DR
This vulnerability allows a malicious app to dynamically register a BroadcastReceiver using System App permissions due to improper input validation in Android's ActiveServices component. This enables local privilege escalation without requiring user interaction. All Android devices running versions 11 through 13 are affected.
💻 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 where an attacker gains SYSTEM-level privileges, allowing installation of persistent malware, data theft, and bypassing all security controls.
Likely Case
Malicious app gains elevated permissions to access sensitive data, modify system settings, or perform unauthorized actions without user knowledge.
If Mitigated
Limited impact due to proper app sandboxing and security controls, but still potential for data leakage or limited privilege escalation.
🎯 Exploit Status
Exploitation requires a malicious app to be installed on the device. No user interaction needed after installation. The vulnerability is in the Android framework itself.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin April 2023 patches
Vendor Advisory: https://source.android.com/security/bulletin/2023-04-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > System update. 2. Install the April 2023 security patch or later. 3. Restart the device after installation. 4. For enterprise devices, coordinate with MDM provider for managed updates.
🔧 Temporary Workarounds
Restrict app installations
androidPrevent installation of apps from unknown sources to reduce attack surface
Settings > Security > Install unknown apps > Disable for all apps
Use Android Enterprise recommendations
androidImplement app allowlisting and security policies for managed devices
🧯 If You Can't Patch
- Isolate affected devices from sensitive networks and data
- Implement strict app control policies and monitor for suspicious app behavior
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If version is 11, 12, 12L, or 13 without April 2023 security patch, device is vulnerable.Check Version:
adb shell getprop ro.build.version.release && adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify Android version has security patch level of April 2023 or later in Settings > About phone > Android security patch level.📡 Detection & Monitoring
Log Indicators:
- Unusual BroadcastReceiver registrations with system permissions
- Logcat entries showing permission escalation attempts in ActiveServices
Network Indicators:
- Not applicable - local vulnerability
SIEM Query:
Not applicable for typical Android deployments. For enterprise MDM, monitor for unexpected permission changes or app behavior anomalies.