Securing Water Treatment ICS: A Guide Based on the Polish Security Agency Report

Overview

In a recent incident, the Polish Security Agency reported that hackers breached industrial control systems (ICS) at five water treatment plants. Attackers gained the ability to modify operational parameters of critical equipment, directly risking public water supply safety. This tutorial translates that wake-up call into actionable guidance for facility managers, IT/OT security teams, and engineers. You'll learn how to prevent, detect, and respond to such intrusions, using the Polish breach as a case study. By the end, you'll have a structured approach to harden your water treatment ICS against adversaries who target the equipment that keeps water clean and flowing.

Securing Water Treatment ICS: A Guide Based on the Polish Security Agency Report — Source: www.securityweek.com

Prerequisites

Before diving into the step-by-step instructions, ensure you have:

Basic understanding of industrial control systems (SCADA, PLCs, HMIs).
Familiarity with network security concepts (firewalls, segmentation, VPNs).
Access to your own OT network architecture diagrams.
Approval from management to test and implement security changes.
Basic command-line skills for Linux/Windows systems, as some steps involve configuring monitoring tools.

Step-by-Step Guide to Securing Water Treatment ICS

1. Map Your ICS Attack Surface

Start by identifying every device that can change operational parameters—PLC logic, pump speeds, valve positions, chemical dosing rates. The Polish attackers specifically targeted this ability. Use tools like Wireshark or Nessus to discover all endpoints. Document each device's IP, vendor, firmware version, and whether it's directly exposed to corporate IT or the internet. Jump to common mistakes related to misidentified assets.

2. Isolate the OT Network

Implement network segmentation using firewalls with strict rules. The ICS network must be separate from corporate IT and the internet. Use a demilitarized zone (DMZ) for any required data exchange (e.g., operational dashboards to management). Configure ACLs so that only authorized engineers from specific workstations can reach PLCs. Consider a unidirectional gateway (data diode) for outbound-only monitoring data.

3. Harden Access Controls

Create role-based access control (RBAC) for all ICS components. No shared passwords. Use multi-factor authentication (MFA) for remote connections. In the Polish case, hackers likely exploited weak credentials. Implement VPN with certificate-based authentication for any remote maintenance. Regularly audit user accounts and remove dormant ones.

4. Deploy Anomaly Detection

Set up tools that monitor for unexpected parameter changes—e.g., a pump running at 120% speed when max design is 100%. Use open-source solutions like ELK stack with Zeek, or commercial OT-specific platforms. Configure alerts for any write commands to PLCs that are outside maintenance windows. Also log all HMI interactions. Detection of abnormal writes could have stopped the Polish attack earlier.

5. Harden the Control Logic

Protect PLC code with digital signatures or checksums. Regularly compare running firmware against a baseline. Use application whitelisting on engineering workstations. Limit the number of people with code-write privileges. In the Polish breach, attackers manipulated parameters directly—defenses against unauthorized logic changes are critical.

6. Develop an Incident Response Plan

Define procedures for when an anomaly is detected. Include steps to: isolate affected controllers physically (pull network cable), revert to known-good backup configurations, notify authorities (e.g., CERT, police). Conduct tabletop exercises simulating the Polish scenario. Ensure plans address both safety and continuity of water treatment.

Common Mistakes to Avoid

Thinking IT security is enough: OT systems require specialized defenses—patching windows patching windows won't protect legacy PLCs.
Ignoring third-party connections: The Polish breach may have involved a contractor link. Scrutinize all remote access points.
Poor password hygiene: Using vendor defaults or simple passwords.
Over-reliance on monitoring thresholds: Attackers may stay just under the radar—use behavioral anomaly detection too.
Not backing up configurations: Without offline backups, recovery after parameter modification is slow and risky.

Summary

The Polish water treatment plant breaches underscore how attackers can gain direct control over public health infrastructure by modifying ICS parameters. This guide provided a structured approach—mapping assets, segmenting networks, hardening access, deploying anomaly detection, protecting control logic, and preparing incident response. Implement these steps proactively to keep your facility's water safe and your operations secure.