CVE-2021-44411
📋 TL;DR
CVE-2021-44411 is a denial-of-service vulnerability in Reolink RLC-410W cameras where a specially crafted HTTP request to the cgiserver.cgi JSON parser causes the device to reboot. This affects Reolink RLC-410W v3.0.0.136_20121102 firmware users, allowing attackers to disrupt camera functionality.
💻 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, disrupting security monitoring and potentially creating blind spots in surveillance coverage.
Likely Case
Temporary camera reboots causing brief surveillance gaps, potentially during critical security events.
If Mitigated
Minimal impact with proper network segmentation and access controls preventing external exploitation.
🎯 Exploit Status
The vulnerability requires sending a malformed HTTP request with specific JSON parameters; exploit details are documented in the Talos Intelligence report.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with Reolink for updated firmware
Vendor Advisory: https://www.reolink.com/security/
Restart Required: Yes
Instructions:
1. Check Reolink's security advisory for patched firmware. 2. Download the updated firmware from Reolink's official website. 3. Upload and install the firmware through the camera's web interface. 4. Verify the camera reboots successfully with the new version.
🔧 Temporary Workarounds
Network Segmentation
allIsolate cameras on a separate VLAN with restricted access to prevent external exploitation.
Firewall Rules
linuxBlock external HTTP access to camera management interfaces.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Implement strict network access controls to prevent unauthorized HTTP requests to camera interfaces.
- Monitor for reboot events and suspicious HTTP traffic patterns to detect exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check firmware version in camera web interface: Settings > System > Device Information. If version is v3.0.0.136_20121102, device is vulnerable.Check Version:
Check via web interface or use HTTP request to device status endpoint if API available.Verify Fix Applied:
After firmware update, verify version has changed from v3.0.0.136_20121102 to a newer patched version.📡 Detection & Monitoring
Log Indicators:
- Unexpected camera reboots
- HTTP requests with malformed JSON to cgiserver.cgi
Network Indicators:
- HTTP POST requests to /cgi-bin/cgiserver.cgi with unusual JSON payloads
SIEM Query:
source="camera_logs" AND (event="reboot" OR uri="/cgi-bin/cgiserver.cgi")