CVE-2025-34066

Executive Summary

CVE-2025-34066 is a critical security advisory affecting AVTECH IP cameras, DVRs, and NVRs. The vulnerability stems from the use of wget with the --no-check-certificate flag in scripts such as SyncCloudAccount.sh and SyncPermit.sh. This improper certificate validation allows an attacker to perform man-in-the-middle (MITM) attacks on HTTPS communications, potentially intercepting or modifying sensitive data. The vulnerability is unpatched, and no official fix has been released by AVTECH. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant due to the widespread use of these devices in surveillance systems.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, but this is likely a placeholder. Based on the nature of the vulnerability (improper certificate validation leading to MITM), a reasonable CVSS v3.1 vector would be:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
This yields a score of 9.1 (Critical).

• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality: High
• Integrity: High
• Availability: None

The threat level is Critical due to the potential for data interception and manipulation without user interaction.

Deep Dive & Mechanics

The vulnerability is rooted in the use of wget with the --no-check-certificate flag in AVTECH device scripts. This flag disables SSL/TLS certificate validation, allowing any HTTPS connection to be intercepted by an attacker who can perform a MITM attack. The scripts SyncCloudAccount.sh and SyncPermit.sh are likely used for cloud synchronization and permission management, making them prime targets for exploitation.

Attack Scenario:

1. An attacker gains a position on the network (e.g., via ARP spoofing, rogue Wi-Fi, or compromised router).
2. The attacker intercepts HTTPS traffic from the AVTECH device to its cloud service.
3. Since certificate validation is disabled, the attacker can present a self-signed or forged certificate.
4. The attacker can then read, modify, or inject data into the communication stream.

Impact:

• Credential theft (cloud account credentials).
• Unauthorized access to device configuration.
• Potential for remote code execution if the attacker injects malicious payloads.

Vulnerable vs. Patched Code

Vulnerable Code (from SyncCloudAccount.sh or SyncPermit.sh):

wget --no-check-certificate https://cloud.avtech.com/sync -O /tmp/sync_data

Patched Code (recommended):

wget --ca-certificate=/etc/ssl/certs/ca-certificates.crt https://cloud.avtech.com/sync -O /tmp/sync_data

The patched version uses a proper CA certificate bundle to validate the server’s certificate. However, no official patch has been released by AVTECH.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Network access to the AVTECH device (e.g., same subnet).
• Ability to perform ARP spoofing or DNS poisoning.
• A machine with mitmproxy or bettercap installed.

Exploitation Steps:

1. Set up ARP spoofing to redirect traffic from the AVTECH device to your attacker machine:

   arpspoof -i eth0 -t <target_ip> <gateway_ip>
   

2. Use mitmproxy to intercept HTTPS traffic:

   mitmproxy --mode transparent --listen-port 8080
   

3. Since the device does not validate certificates, mitmproxy will automatically generate a certificate that the device accepts.
4. Capture credentials or modify data in transit.

Example with bettercap:

sudo bettercap -eval "set arp.spoof.targets <target_ip>; arp.spoof on; net.sniff on"

Blue Team

Detection:

• Monitor for ARP spoofing attacks using tools like arpwatch.
• Look for unexpected HTTPS connections from AVTECH devices to unknown IPs.
• Check device logs for repeated certificate errors (though the device may not log them).

Mitigation:

• Isolate AVTECH devices on a separate VLAN with strict firewall rules.
• Use a VPN or SSH tunnel for cloud communications.
• Disable cloud sync features if not required.

Indicators of Compromise (IOCs)

• Network:

  • Unexpected ARP replies (ARP spoofing).
  • HTTPS connections to IPs not matching the legitimate cloud service.
  • Presence of self-signed certificates in traffic.

• Host:

  • Modified SyncCloudAccount.sh or SyncPermit.sh scripts.
  • Unusual processes running wget with --no-check-certificate.

• Logs:

  • Repeated connection attempts to cloud services with certificate warnings (if logging is enabled).

Detection Engineering

YARA Rule

rule CVE_2025_34066_AVTECH_MITM {
    meta:
        description = "Detects AVTECH scripts using wget with --no-check-certificate"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-34066"
    strings:
        $wget_no_check = /wget.*--no-check-certificate/
    condition:
        $wget_no_check
}

Sigma Rule

title: AVTECH wget No Certificate Check
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects execution of wget with --no-check-certificate on AVTECH devices
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/wget'
        CommandLine|contains: '--no-check-certificate'
    condition: selection
falsepositives:
    - Legitimate use in testing environments
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 443 (msg:"CVE-2025-34066 AVTECH MITM - wget no certificate check"; flow:to_server; content:"GET"; http_method; content:"/sync"; http_uri; content:"Host: cloud.avtech.com"; http_header; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate devices: Place AVTECH devices on a separate VLAN with no direct internet access.
2. Disable cloud sync: If not required, disable the cloud synchronization feature.
3. Use a VPN: Route all cloud traffic through a VPN that validates certificates.

Long-term Fix:

• AVTECH must release a firmware update that removes the --no-check-certificate flag and uses proper certificate validation.
• Until then, consider replacing affected devices with alternatives that support secure HTTPS.

Workaround:

• Modify the scripts manually (if you have root access) to use --ca-certificate with a valid CA bundle.
• Example:

  wget --ca-certificate=/etc/ssl/certs/ca-certificates.crt https://cloud.avtech.com/sync -O /tmp/sync_data
  

Valters IT