CVE-2021-32941
📋 TL;DR
This critical vulnerability in Annke N48PBB Network Video Recorders allows remote attackers to execute arbitrary code with root privileges via a stack-based buffer overflow. It affects version 3.4.106 build 200422 and earlier. Organizations using these devices for video surveillance are at risk of complete system compromise.
💻 Affected Systems
- Annke N48PBB Network Video Recorder
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system takeover with root access, allowing attackers to disable security systems, exfiltrate video footage, pivot to internal networks, or deploy ransomware.
Likely Case
Remote code execution leading to surveillance system disruption, data theft, or installation of persistent backdoors.
If Mitigated
Limited impact if devices are isolated in separate VLANs with strict network controls, though risk remains if devices are internet-facing.
🎯 Exploit Status
Public exploit code exists, and the vulnerability requires no authentication, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after 3.4.106 build 200422
Vendor Advisory: https://www.cisa.gov/uscert/ics/advisories/icsa-21-238-02
Restart Required: Yes
Instructions:
1. Contact Annke support for firmware updates. 2. Download latest firmware from vendor portal. 3. Upload firmware via web interface. 4. Reboot device after update completes.
🔧 Temporary Workarounds
Network Isolation
allPlace NVR devices in isolated VLAN with no internet access and strict firewall rules.
Access Control Lists
allImplement strict IP-based access controls to limit connections to trusted management IPs only.
🧯 If You Can't Patch
- Immediately disconnect vulnerable devices from internet and critical networks
- Implement network segmentation with strict firewall rules allowing only necessary traffic
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > Information > Version. If version is 3.4.106 build 200422 or earlier, device is vulnerable.Check Version:
Check via web interface or SSH if enabled: cat /etc/versionVerify Fix Applied:
Verify firmware version shows a version newer than 3.4.106 build 200422 after update.📡 Detection & Monitoring
Log Indicators:
- Unusual process execution, unexpected reboots, or authentication failures from unknown IPs
Network Indicators:
- Unusual outbound connections from NVR, unexpected traffic on non-standard ports
SIEM Query:
source="nvr_logs" AND (event="buffer_overflow" OR event="segmentation_fault" OR process="unexpected_executable")