CVE-2024-33623

Executive Summary

CVE-2024-33623 is a denial of service (DoS) vulnerability affecting the LevelOne WBR-6012 router running firmware version R0.40e6. The flaw resides in the Web Application functionality, where a specially crafted HTTP request can cause the device to reboot. This allows an unauthenticated attacker to disrupt network connectivity and services. The vulnerability has a low CVSS score of 3.7 due to its limited impact (availability only) and the requirement for network access. No public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware issue specific to the LevelOne WBR-6012 router.

CVSS Breakdown & Threat Level

• CVSS Score: 3.7 (Low)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication is needed.
• User Interaction: None (UI:N) – No user action is required.
• Scope: Unchanged (S:U) – The impact is confined to the vulnerable component.
• Confidentiality Impact: None (C:N) – No data exposure.
• Integrity Impact: None (I:N) – No data modification.
• Availability Impact: Low (A:L) – The device reboots, causing temporary service disruption.

Threat Level: Low. The vulnerability only causes a reboot, not persistent damage or data loss. However, repeated exploitation could lead to sustained denial of service.

Deep Dive & Mechanics

The vulnerability is triggered by sending a specially crafted HTTP request to the web management interface of the LevelOne WBR-6012 router. The exact mechanism is not publicly documented, but it likely involves improper input validation in the HTTP request parsing logic. When the router processes the malicious request, it enters an undefined state that forces a system reboot.

Root Cause: Insufficient validation of HTTP request parameters or headers, leading to a buffer overflow, null pointer dereference, or other memory corruption that crashes the web server process and triggers a watchdog reboot.

Attack Vector: An attacker on the same network (or remotely if the web interface is exposed) sends a single HTTP request to the router's IP address on port 80 (or 443 if HTTPS is enabled).

Impact: The router reboots, causing all connected devices to lose internet access and internal network connectivity for approximately 1-2 minutes (typical router boot time). This can be repeated to cause persistent disruption.

Vulnerable vs. Patched Code

No patched code is available. The vulnerable firmware version is R0.40e6. The following is a hypothetical vulnerable code snippet and a patched version for illustrative purposes.

Vulnerable Code (hypothetical):

void handle_http_request(char *request) {
    char buffer[1024];
    // No bounds checking
    strcpy(buffer, request);
    // Process buffer...
}

Patched Code (hypothetical):

void handle_http_request(char *request) {
    char buffer[1024];
    // Bounds checking
    strncpy(buffer, request, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0';
    // Process buffer...
}

Exploitation & Lab Setup

Red Team

Objective: Cause a denial of service by rebooting the LevelOne WBR-6012 router.

Prerequisites:

• Network access to the router's web interface (default IP: 192.168.1.1).
• No authentication required.

Exploit Steps:

1. Identify the target router's IP address (e.g., via ARP scan or network discovery).
2. Send a specially crafted HTTP request. Since no public exploit exists, the exact payload is unknown. A generic example using curl:

   curl -X GET "http://192.168.1.1/cgi-bin/reboot?payload=<malicious_data>"
   

   Or using a Python script:

   import socket
   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   s.connect(("192.168.1.1", 80))
   s.send(b"GET /cgi-bin/reboot?payload=<malicious_data> HTTP/1.1\r\nHost: 192.168.1.1\r\n\r\n")
   s.close()
   

3. Monitor the router's response. If successful, the router will reboot, and network connectivity will be lost temporarily.

Note: The exact payload is not publicly known. This is a placeholder for demonstration.

Blue Team

Detection:

• Monitor for unusual HTTP requests to the router's web interface, especially those with long or malformed parameters.
• Use network intrusion detection systems (NIDS) to flag requests to /cgi-bin/reboot or similar endpoints.

Mitigation:

• Disable remote management of the router if not needed.
• Restrict access to the web interface to trusted IP addresses only.
• Apply firmware updates if/when available.
• Implement rate limiting on the web interface to prevent rapid exploitation.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests to the router's IP address with unusual payloads or long strings.
  • Repeated connection attempts to port 80/443 of the router.
• System:
  • Router logs showing unexpected reboots or crashes.
  • Syslog entries indicating a watchdog reset.
• File:
  • No file-based IOCs as this is a network-based attack.

Detection Engineering

YARA Rule

rule CVE_2024_33623_HTTP_DoS {
    meta:
        description = "Detects HTTP requests targeting LevelOne WBR-6012 reboot vulnerability"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-33623"
    strings:
        $reboot = "/cgi-bin/reboot" nocase
        $malicious = "payload=" nocase
    condition:
        $reboot and $malicious
}

Sigma Rule

title: CVE-2024-33623 HTTP DoS Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests targeting LevelOne WBR-6012 reboot vulnerability
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/cgi-bin/reboot"
    condition: selection
falsepositives:
    - Legitimate administrative actions
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-33623 LevelOne WBR-6012 DoS Attempt"; flow:to_server; content:"/cgi-bin/reboot"; http_uri; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Remote Management: If the web interface is accessible from the internet, disable remote management immediately.
2. Restrict Access: Use firewall rules to allow only trusted IP addresses to access the router's web interface.
3. Monitor Logs: Enable logging on the router and monitor for unexpected reboots or suspicious HTTP requests.

Long-Term Actions:

1. Firmware Update: Check the LevelOne website for a patched firmware version. If none is available, consider replacing the router with a more secure model.
2. Network Segmentation: Place IoT devices like routers on a separate VLAN to limit exposure.
3. IDS/IPS: Deploy network intrusion detection/prevention systems to block malicious HTTP requests.

Workaround: If patching is not possible, disable the web interface entirely and manage the router via SSH or serial console if supported.

Valters IT
Securing Digital Frontiers