CVE-2021-44397 – This vulnerability allows remote attackers to c... (How to Fix)

Q: What is the severity of CVE-2021-44397?

CVE-2021-44397 has a CVSS score of 7.7 (HIGH). This vulnerability allows remote attackers to cause a denial of service by sending a specially crafted HTTP request to the Reolink RLC-410W camera's cgiserver.cgi JSON command parser. The camera will reboot when exploited, disrupting video surveillance functionality. Only Reolink RLC-410W cameras running vulnerable firmware are affected.

📋 TL;DR

This vulnerability allows remote attackers to cause a denial of service by sending a specially crafted HTTP request to the Reolink RLC-410W camera's cgiserver.cgi JSON command parser. The camera will reboot when exploited, disrupting video surveillance functionality. Only Reolink RLC-410W cameras running vulnerable firmware are affected.

💻 Affected Systems

Products:

Reolink RLC-410W

Versions: v3.0.0.136_20121102

Operating Systems: Embedded Linux firmware

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects the specific firmware version mentioned; other Reolink models or firmware versions may not be vulnerable.

📦 What is this software?

Rlc 410w Firmware by Reolink

View all CVEs affecting Rlc 410w Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Persistent attacker could repeatedly reboot the camera, rendering it unusable for surveillance and potentially causing physical security gaps during critical moments.

🟠

Likely Case

Temporary loss of video surveillance capability during camera reboot cycles, with potential data loss from missed recording periods.

🟢

If Mitigated

Minimal impact if camera is behind firewall with restricted HTTP access or if patched firmware is installed.

🌐 Internet-Facing: HIGH - The vulnerability is triggered via HTTP requests, making internet-exposed cameras immediately vulnerable to exploitation.

🏢 Internal Only: MEDIUM - Internal attackers or malware could still exploit this, but requires network access to the camera's management interface.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The vulnerability requires sending a malformed HTTP request with specific parameters, which is trivial to automate. No authentication is required.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Firmware newer than v3.0.0.136_20121102

Vendor Advisory: https://support.reolink.com/hc/en-us/articles/360049010514

Restart Required: Yes

Instructions:

1. Log into Reolink camera web interface. 2. Navigate to System > Maintenance. 3. Click 'Check for Updates' or manually upload latest firmware. 4. Apply update and allow camera to reboot.

🔧 Temporary Workarounds

Network Segmentation

linux

Restrict HTTP access to camera management interface

iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

Disable Remote Access

all

Turn off UPnP and port forwarding for camera

🧯 If You Can't Patch

Place camera behind firewall with strict inbound rules allowing only trusted IPs to access HTTP management interface
Disable cloud/remote access features and use only local network monitoring

🔍 How to Verify

Check if Vulnerable:

Check firmware version in camera web interface under System > Device Information. If version is exactly v3.0.0.136_20121102, device is vulnerable.

Check Version:

curl -s http://CAMERA_IP/cgi-bin/cgiserver.cgi?cmd=getDevInfo | grep -i version

Verify Fix Applied:

After updating, verify firmware version shows newer than v3.0.0.136_20121102 and test by attempting to send crafted HTTP request to cgiserver.cgi endpoint.

📡 Detection & Monitoring

Log Indicators:

Multiple reboot events in system logs
HTTP requests to cgiserver.cgi with rtmp=start parameter

Network Indicators:

HTTP POST/GET requests to /cgi-bin/cgiserver.cgi containing malformed JSON or rtmp parameters
Unusual reboot patterns from camera IP

SIEM Query:

source="camera_logs" AND (event="reboot" OR uri="/cgi-bin/cgiserver.cgi") | stats count by src_ip

📊 Metadata

CVE ID: CVE-2021-44397

CVSS v3 Score: 7.7 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

CWE: CWE-20

Published: January 28, 2022

Last Updated: November 21, 2024

🔗 References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1421 Exploit,Technical Description,Third Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1421 Exploit,Technical Description,Third Party Advisory

📤 Share & Export

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