Dahua IP Camera and NVR/DVR Authentication Bypass Vulnerability (CVE-2021-33044) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTCertain Dahua IP cameras, NVRs, DVRs, and associated firmware versions
Attackers can completely bypass the identity authentication process during login and gain full administrative control of the device
Immediately apply the latest firmware updates provided by the vendor and restrict external network access to the devices
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Download the appropriate patched firmware for your specific device model from the official Dahua Security Support portal. If CLI or API access is available, you can trigger the upgrade process using the following command structure:
# Example command to trigger firmware upgrade via Dahua API (adjust parameters to match your environment)
curl -X POST -u 'admin:YOUR_NEW_PASSWORD' \
'http://[DEVICE_IP]/cgi-bin/upgrade.cgi?action=start' \
-H 'Content-Type: application/octet-stream' \
--data-binary '@/path/to/dahua_firmware_patched.bin'2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, isolate the devices from the public internet. Implement strict firewall rules to restrict access to authorized management workstations or require a secure VPN connection.
# Restrict access to Dahua service ports (37777, 80) using iptables
iptables -A INPUT -p tcp -s 192.168.1.100 --dport 37777 -j ACCEPT
iptables -A INPUT -p tcp -s 192.168.1.100 --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 37777 -j DROP
iptables -A INPUT -p tcp --dport 80 -j DROP3. Log Audit & IoC Verification Commands
Monitor network traffic for anomalous connection attempts to port 37777. Use the following scanning command to identify exposed Dahua devices within your local network subnet:
# Scan local subnet to identify active Dahua devices on port 37777
nmap -p 37777 --open -sV 192.168.1.0/24Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-33044) is a critical identity authentication bypass (CWE-287) discovered in the login process of several Dahua products. The root cause lies in the insufficient validation of specific data packets transmitted during the authentication handshake, allowing attackers to bypass security checks without providing valid credentials.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by sending specially crafted malicious data packets to the device's login service port (typically TCP port 37777 or HTTP port 80). The device's authentication module processes these packets incorrectly, granting the attacker an authenticated session. Once bypassed, the attacker gains administrative privileges, enabling unauthorized video stream access, configuration changes, or device takeover.
3. Infrastructure & Business Impact
With a CVSS score of 9.8 (Critical) and its inclusion in the CISA KEV (Known Exploited Vulnerabilities) catalog, this vulnerability poses an immediate threat as it is actively exploited in the wild. Compromising physical security assets like IP cameras and NVRs can lead to severe privacy breaches, physical security failures, and serve as an entry point for lateral movement within the corporate network.
Official Vendor Advisories & References
The identity authentication bypass vulnerability found in some Dahua products during the login process. Attackers can bypass device identity authentication by constructing malicious data packets.
Frequently Asked SecOps Questions (CVE-2021-33044)
FAQQ1. How critical is CVE-2021-33044 and is it actively exploited in the wild?
CVE-2021-33044 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 100.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-33044?
Primary impacted vendors include dahua across ip camera, nvr, dvr. Scope summary: Select Dahua IP Cameras, NVRs, and DVRs running firmware versions released prior to September 2021
Q3. What temporary mitigations or workarounds exist for CVE-2021-33044 before patching?
[Mitigation] Immediately apply the latest firmware updates provided by the vendor and restrict external network access to the devices Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-33044
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