CVE-2021-21736
📋 TL;DR
This vulnerability in ZTE smart cameras allows users whose sharing permissions have been revoked to still control the camera remotely through the cloud app. Attackers can perform actions like restarting the camera or restoring factory settings. This affects ZTE ZXHN HS562 camera models with specific firmware versions.
💻 Affected Systems
- ZTE ZXHN HS562 Smart Camera
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker with previously revoked access could factory reset the camera, disable security monitoring, or disrupt surveillance operations.
Likely Case
Formerly authorized users who should no longer have access can still control camera functions remotely.
If Mitigated
With proper access control enforcement, only current authorized users can control camera functions.
🎯 Exploit Status
Exploitation requires access credentials from a user who was previously granted sharing permissions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with ZTE for updated firmware
Vendor Advisory: https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1015964
Restart Required: Yes
Instructions:
1. Check ZTE support for firmware updates. 2. Download latest firmware. 3. Apply update through camera management interface. 4. Restart camera.
🔧 Temporary Workarounds
Disable Cloud Sharing
allDisable all user sharing features in the camera cloud app to prevent exploitation.
Revoke and Re-add Users
allCompletely remove all shared users and re-add only current authorized users.
🧯 If You Can't Patch
- Disconnect camera from cloud services and use only local network access
- Implement network segmentation to isolate cameras from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check firmware version in camera web interface or mobile app against affected versions.Check Version:
Check camera web interface at System > Firmware or similar menuVerify Fix Applied:
Test if revoked users can still access camera controls after applying firmware update.📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts from previously authorized users
- Factory reset or restart commands from unexpected sources
Network Indicators:
- Cloud API calls from revoked user accounts
- Unexpected camera control commands
SIEM Query:
source="camera_logs" AND (event="factory_reset" OR event="restart") AND user_status="revoked"