CVE-2021-44401
📋 TL;DR
A denial-of-service vulnerability in Reolink RLC-410W cameras allows attackers to cause device reboots by sending specially crafted HTTP requests to the cgiserver.cgi JSON parser. This affects Reolink RLC-410W v3.0.0.136_20121102 firmware users, potentially disrupting camera functionality and surveillance coverage.
💻 Affected Systems
- Reolink RLC-410W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Persistent denial-of-service attacks could render cameras unusable for extended periods, compromising physical security monitoring and creating blind spots in surveillance coverage.
Likely Case
Temporary camera reboots causing surveillance gaps of 1-2 minutes during restart cycles, potentially missing critical events.
If Mitigated
Minimal impact with proper network segmentation and access controls preventing unauthorized HTTP requests to camera interfaces.
🎯 Exploit Status
Exploitation requires sending malformed JSON in HTTP requests to the cgiserver.cgi endpoint; no authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Reolink for updated firmware
Vendor Advisory: https://reolink.com/support/security-advisory/
Restart Required: Yes
Instructions:
1. Log into camera web interface 2. Navigate to System > Maintenance 3. Check for firmware updates 4. Download and install latest firmware 5. Reboot camera after update
🔧 Temporary Workarounds
Network Segmentation
allIsolate cameras on separate VLANs with strict firewall rules preventing external access to camera web interfaces.
Access Control Lists
allImplement IP-based restrictions allowing only authorized management systems to communicate with camera HTTP interfaces.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate cameras from untrusted networks
- Deploy network-based intrusion prevention systems to detect and block malicious HTTP requests to cgiserver.cgi
🔍 How to Verify
Check if Vulnerable:
Check firmware version in camera web interface under System > Device InformationCheck Version:
curl -s http://[camera-ip]/cgi-bin/systeminfo.cgi | grep FirmwareVerify Fix Applied:
Verify firmware version is updated beyond v3.0.0.136_20121102 and test with known exploit payloads📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /cgi-bin/cgiserver.cgi with malformed JSON
- Unexpected camera reboot events in system logs
Network Indicators:
- HTTP POST requests to camera IP on port 80 with PtzCtrl parameter containing non-object JSON values
SIEM Query:
source="camera-logs" AND (uri="/cgi-bin/cgiserver.cgi" AND (body="PtzCtrl" AND NOT body="\"PtzCtrl\":{"))