CVE-2023-21071
📋 TL;DR
This CVE describes a kernel-level vulnerability in Android's dhd_msgbuf.c driver where improper input validation allows an out-of-bounds write. An attacker with local access and system execution privileges could exploit this to escalate privileges without user interaction. This affects Android devices running vulnerable kernel versions.
💻 Affected Systems
- Android
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Local attacker gains full root/system privileges, potentially compromising the entire device, accessing sensitive data, and establishing persistence.
Likely Case
Malicious app or local user exploits the vulnerability to gain elevated privileges, bypassing Android's security sandbox and accessing restricted resources.
If Mitigated
With proper kernel hardening and SELinux policies, exploitation becomes more difficult, potentially limiting impact to specific processes or requiring additional vulnerabilities.
🎯 Exploit Status
Requires local access and system execution privileges; kernel-level exploitation typically requires specific knowledge of memory layout and offsets.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: March 2023 Android Security Bulletin patches
Vendor Advisory: https://source.android.com/security/bulletin/pixel/2023-03-01
Restart Required: Yes
Instructions:
1. Apply March 2023 Android Security Bulletin patches. 2. Update Android kernel to patched version. 3. Reboot device to load patched kernel.
🔧 Temporary Workarounds
Restrict system execution privileges
androidLimit which processes/applications can obtain system execution privileges through SELinux policies and app sandboxing.
🧯 If You Can't Patch
- Implement strict SELinux policies to limit privilege escalation impact
- Monitor for suspicious privilege escalation attempts using Android security logging
🔍 How to Verify
Check if Vulnerable:
Check Android kernel version and security patch level in Settings > About phone > Android versionCheck Version:
adb shell getprop ro.build.version.security_patchVerify Fix Applied:
Verify security patch level is March 2023 or later in Settings > About phone📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- SELinux denials for privilege escalation attempts
- Unexpected process privilege changes
SIEM Query:
source="android_kernel" AND (event_type="panic" OR event_type="oops")