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Introduction:
The convergence of Operational Technology (OT) and Information Technology (IT) security is no longer a niche concern but a critical boardroom imperative. Recent networking events hosted by French cybersecurity leaders XMCO and TheGreenBow in Toulouse’s IoT Valley highlight a growing trend: the fusion of casual technical exchange with serious defense strategies, particularly in sectors like aviation where XMCO serves as a CERT provider. This article transforms the spirit of that collaborative meetup into a technical deep dive, extracting core lessons on Cyber Threat Intelligence (CTI), VPN hardening, and the security architecture required to protect critical infrastructure in 2026.
Learning Objectives:
- Understand how to deploy and harden IPSec VPNs (TheGreenBow) for secure OT/IT connectivity.
- Learn to integrate OSINT frameworks like MISP with threat intelligence feeds for proactive defense.
- Master Linux and Windows command-line techniques for analyzing network traffic and detecting anomalies in mixed environments.
You Should Know:
1. Hardening IPSec VPN Gateways for OT Environments
TheGreenBow specializes in VPN solutions, which are often the gateway between industrial control systems (ICS) and corporate networks. Misconfigurations here can lead to catastrophic breaches. A common scenario involves setting up a site-to-site VPN to allow a remote engineer to access a PLC (Programmable Logic Controller) without exposing the device to the open internet.
Step-by-step guide:
Objective: Configure an IPSec VPN with strict access controls using a Linux-based strongSwan server (representing the OT gateway) and a Windows client (TheGreenBow equivalent).
1. Install strongSwan on Linux (Ubuntu/Debian):
sudo apt update && sudo apt install strongswan strongswan-pki libcharon-extra-plugins -y
2. Generate Certificates for Mutual Authentication:
Generate a CA key and certificate ipsec pki --gen --type rsa --size 4096 --outform pem > ca-key.pem ipsec pki --self --ca --lifetime 3650 --in ca-key.pem --dn "CN=VPN CA" --outform pem > ca-cert.pem Generate server certificate ipsec pki --gen --type rsa --size 2048 --outform pem > server-key.pem ipsec pki --pub --in server-key.pem | ipsec pki --issue --lifetime 1825 --cacert ca-cert.pem --cakey ca-key.pem --dn "CN=vpn.example.com" --san=vpn.example.com --flag serverAuth --flag clientAuth --outform pem > server-cert.pem
3. Configure IPsec (`/etc/ipsec.conf`):
conn ot-to-it left=%defaultroute leftcert=server-cert.pem leftsubnet=192.168.10.0/24 OT Network right=%any rightid="C=FR, O=TheGreenBow, CN=client" rightauth=pubkey rightsubnet=10.0.0.0/16 IT Network access auto=add keyexchange=ikev2 ike=aes256-sha256-modp2048! esp=aes256-sha256!
4. Windows Client Configuration:
- In TheGreenBow VPN client, import the CA certificate into the “Trusted Root Certification Authorities” store.
- Configure the connection to use “IKEv2” with “Certificate” authentication, pointing to the issued client certificate.
What This Does: This setup ensures that only authenticated devices with valid certificates can bridge the OT and IT networks, preventing unauthorized lateral movement. The use of IKEv2 with strong ciphers mitigates downgrade attacks common in legacy VPN deployments.
- Deploying Threat Intelligence Feeds with MISP (XMCO Context)
XMCO operates as a CERT for the aviation sector, relying heavily on structured threat intelligence. A core skill is setting up a MISP (Malware Information Sharing Platform) instance to ingest, correlate, and act on indicators of compromise (IOCs).
Step-by-step guide:
Objective: Install MISP on Ubuntu 22.04 LTS and integrate a free OSINT feed to automate threat detection.
1. Install Dependencies and MISP:
Install prerequisites sudo apt-get install -y gcc git make redis-server mariadb-client mariadb-server python3-pip Clone MISP (Official install script approach) cd /var/www/ sudo git clone https://github.com/MISP/MISP.git cd MISP sudo bash install.sh
2. Configure Feeds:
- Log into the MISP web interface (default admin:admin).
- Navigate to `Sync Actions` ->
Feeds. - Add a new feed: Choose “CIRCL OSINT Feed” or “AlienVault OTX” (free tier).
- Set the `Distribution` to “Your organization only” for internal testing.
- Click “Fetch & store all events” to populate the database with live IOCs.
3. Automate Local Blocking via Linux:
Create a script to fetch MISP events and block IPs via iptables (for a perimeter firewall):
!/bin/bash
fetch_iocs.sh
API_KEY="YOUR_MISP_API_KEY"
MISP_URL="https://localhost/events/restSearch.json"
curl -k -H "Authorization: $API_KEY" -H "Accept: application/json" $MISP_URL -d '{"returnFormat":"json","tags":["malicious"],"eventinfo":""}' -o /tmp/iocs.json
Parse and block IPs (simplified)
cat /tmp/iocs.json | jq -r '.response[].Attribute[] | select(.type=="ip-dst") | .value' | sort -u | while read ip; do
sudo iptables -A INPUT -s $ip -j DROP
done
What This Does: This turns raw threat data into actionable defense. By automating the ingestion of IOCs from trusted communities (similar to the collaboration fostered at the Toulouse event), defenders can preemptively block connections to known command-and-control servers before an endpoint even attempts to reach them.
- Windows Event Log Analysis for Lateral Movement Detection
In a mixed environment where both Linux servers (OT) and Windows workstations (IT) interact, detecting lateral movement is key. A common technique involves hunting for suspicious PowerShell execution or service creation events.
Step-by-step guide:
Objective: Use `wevtutil` and PowerShell to query security logs for indicators of credential dumping (like Mimikatz) or unauthorized VPN access.
- Enable Advanced Audit Logging via GPO or Command Line:
Enable PowerShell logging Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" -Name "EnableScriptBlockLogging" -Value 1 Enable Process Creation auditing (Event ID 4688) auditpol /set /subcategory:"Process Creation" /success:enable /failure:enable
2. Query for Suspicious Service Installations (Potential Persistence):
Using Get-WinEvent to find new services created via sc.exe
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4697} | Where-Object { $<em>.Message -like "sc.exe" -or $</em>.Message -like "powershell" } | Select-Object TimeCreated, Message
3. Linux Side: Monitoring for VPN Tunnel Changes
On the strongSwan server, monitor connection logs for unexpected peer additions:
Watch live IPSec logs sudo journalctl -fu strongswan | grep -E "connecting|disconnecting|authentication failed" Create a cron job to alert on new connections /5 grep "ESTABLISHED" /var/log/charon.log | tail -5 | mail -s "VPN New Connections" [email protected]
What This Does: This provides a dual-sided view of the network. While Windows logs reveal what an attacker does after compromising a workstation, Linux VPN logs reveal the bridge they attempt to use to reach critical OT assets. Combining these gives the “shared knowledge” benefit referenced in the XMCO/TheGreenBow partnership.
4. API Security in Critical Infrastructure
Modern ICS environments rely on APIs for monitoring and control. XMCO’s involvement with aviation CERTs implies a need to secure these interfaces against injection and denial-of-service attacks.
Step-by-step guide:
Objective: Test an API endpoint for common misconfigurations using `curl` and Python, and apply mitigation headers.
1. Reconnaissance (Linux):
Check for exposed endpoints and missing authentication curl -k -X GET https://target-ics.local/api/v1/status -H "Authorization: Bearer test" -v Look for verbose errors indicating SQL (e.g., "MySQL error")
- Rate Limiting Mitigation with Nginx (as a reverse proxy in front of OT APIs):
/etc/nginx/sites-available/api-gateway limit_req_zone $binary_remote_addr zone=login:10m rate=10r/m; server { location /api/ { limit_req zone=login burst=5 nodelay; proxy_pass http://internal-ot-server:8080; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } }
Command to reload: `sudo nginx -s reload`
What This Does: This approach places a “shield” in front of sensitive OT APIs. Rate limiting prevents automated brute-force attacks (e.g., trying to manipulate valve states), while the proxy hides the internal architecture, a critical concept when collaborating with third-party vendors like TheGreenBow for secure remote access.
5. Cloud Hardening for Hybrid OT/IT Visibility
As organizations embrace the cloud for centralized logging (SIEM), ensuring the security of the data pipeline is paramount. This mirrors the “sharing” ethos of the Toulouse event but applied to data.
Step-by-step guide:
Objective: Securely ship Windows Event Logs to an AWS S3 bucket for analysis, using IAM roles and client-side encryption.
- On Windows, install AWS CLI and configure with an IAM role (no static keys):
Install AWS Tools Install-Module -Name AWS.Tools.Installer Install-AWSToolsModule AWS.Tools.S3, AWS.Tools.SecurityToken Assume role and upload logs $Logs = Get-WinEvent -LogName Security -MaxEvents 100 | Export-Clixml -Path C:\temp\events.xml Write-S3Object -BucketName "cyber-ot-logs" -File "C:\temp\events.xml" -Key "security/$(Get-Date -Format 'yyyy-MM-dd-HH')/events.xml" -ServerSideEncryption AES256
-
On Linux (AWS CLI), enforce bucket policies to prevent deletion:
Create a bucket policy denying delete unless MFA is present aws s3api put-bucket-policy --bucket cyber-ot-logs --policy file://policy.json where policy.json contains: {"Version":"2012-10-17","Statement":[{"Effect":"Deny","Action":"s3:DeleteObject","Principal":"","Resource":"arn:aws:s3:::cyber-ot-logs/","Condition":{"Bool":{"aws:MultiFactorAuthPresent":"false"}}}]}
What This Does: This ensures that even if an attacker compromises the logging server, they cannot tamper with historical forensic data. Client-side encryption adds a layer of security, ensuring that only the intended security team (the “CISO, CIO, CSO” attendees from the post) can decrypt sensitive event logs.
What Undercode Say:
- Collaboration is a Force Multiplier: The informal event in Toulouse underscores a key cybersecurity truth—technical defense is strengthened by community. The combination of XMCO’s CTI expertise and TheGreenBow’s secure connectivity tools creates a robust model for defending critical sectors like aviation.
- Defense Requires Integration: Isolated tools fail. Effective security in 2026 requires integrating VPN telemetry, OSINT feeds, endpoint logs, and cloud storage into a cohesive workflow, turning raw data into actionable intelligence that can be shared among trusted peers.
Prediction:
As geopolitical tensions rise, the attack surface in critical infrastructure will continue to expand, making events like the XMCO/TheGreenBow meetup not just social gatherings but essential strategy sessions. We predict a significant increase in “collective defense” models where CERTs, vendors, and end-users share real-time threat data through automated platforms. The future of OT security will rely less on proprietary silos and more on open standards and community-driven resilience, turning a “beer on the canal” into the next evolution of cyber defense.
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Reported By: Yohann Bauzil – Hackers Feeds
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