CVE-2021-39677
📋 TL;DR
This vulnerability allows attackers to read memory outside the allocated buffer when the camera buffer size is zero, potentially exposing sensitive information. It affects Android 11 devices with vulnerable camera implementations. Attackers could exploit this to leak process memory or cause application crashes.
💻 Affected Systems
- Android devices with vulnerable camera implementations
📦 What is this software?
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, data exfiltration, or persistent malware installation
Likely Case
Information disclosure of sensitive memory contents, application crashes, or denial of service
If Mitigated
Limited impact with proper sandboxing and memory protection mechanisms in place
🎯 Exploit Status
Requires app with camera permissions to trigger the vulnerable code path
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Android Security Bulletin February 2022 or later
Vendor Advisory: https://source.android.com/security/bulletin/aaos/2022-02-01
Restart Required: Yes
Instructions:
1. Check for Android system updates in Settings > System > System update. 2. Install the February 2022 security patch or later. 3. Reboot device after installation.
🔧 Temporary Workarounds
Disable camera permissions for untrusted apps
androidPrevent unauthorized apps from accessing camera functionality
Settings > Apps > [App Name] > Permissions > Camera > Deny
🧯 If You Can't Patch
- Restrict installation of untrusted applications from unknown sources
- Use mobile device management (MDM) to enforce security policies and app whitelisting
🔍 How to Verify
Check if Vulnerable:
Check Android version in Settings > About phone > Android version. If version is 11 and security patch level is before February 2022, 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 is 11 with security patch level February 2022 or later in Settings > About phone > Android security update📡 Detection & Monitoring
Log Indicators:
- Camera service crashes
- Out of bounds memory access errors in system logs
- SIGSEGV signals from camera processes
Network Indicators:
- Unusual camera activation patterns
- Suspicious app behavior with camera permissions
SIEM Query:
source="android_logs" AND ("camera" AND ("crash" OR "segfault" OR "OOB"))