7 SCADA Security Best Practices: How to Protect Your Systems

Back in the day, SCADA systems were limited to performing operations on-site. Despite this negatively affecting flexibility, it made SCADA systems relatively safe from cyber threats. Fast forward to today, with the internet boom and the new trend of combining SCADA with IoT (Internet of Things), things have gotten a tad more complicated.

SCADA is now using IoT devices that, as their name suggests, are connected to the internet. This exposes your SCADA system to potential security risks.

So, what’s the plan?

In this blog post, we’re laying out seven SCADA security best practices to help you keep your system secure and running smoothly. Let’s dive in.

#1. Network Segmentation and Isolation

Network segmentation is when you divide a computer network into subnetworks or isolated segments. Each of these segments operates independently and has restricted access to other segments.
To achieve network segmentation, you can use firewalls or control traffic from one section to another using Access Control Lists (ACLs) with routers.

In SCADA systems, there are more critical components than others. So, when you use network segmentation for the security of your SCADA system, you can:

• Limit the entry points available to potential attackers. Even if one malicious actor has access to one network segment, it’s going to be harder to move on to the next one.
• Detect suspicious activities more easily. You can analyze traffic within each segment separately. This makes it simpler to spot potential security breaches.

Another plus of using network segmentation is that it allows you to implement access control policies which we will address next.

#2. Access Control Measures

Access control measures are a security technique to manage users based on their credentials and give them permission to access specific areas on a network. Some of the most popular access control methods include:

• Role-Based Access Control (RBAC): This method defines access to the network based on the user’s job role. The higher the responsibility of a role, the more access rights this user may have to the network. For example, an engineer has different access rights (according to their responsibilities) from an operator.
• Multi-Factor Authentication (MFA): In this method, you gain access to the network by providing two or more methods of authentication. A typical example of this is when you have to enter a password first and then you get a text message to your phone with a code you need to enter to gain access.

Security in SCADA systems often involves multiple user roles such as engineers, operators, or administrators. The use of access control measures in SCADA allows you to:

• Limit the actions and access to prevent any insider threats.
• Facilitate the audit and tracking of user actions.
• Reduce the risk of access from unauthorized users using stolen credentials.

#3. Regular Patching and Updates

Software vendors send regular patches or updates to address vulnerabilities and improve the functionality of your system. Applying these patches/updates regularly is an important practice in ensuring the cyber security and performance of SCADA systems.

Not only that but regularly updating your SCADA components helps you:

• Reduce the need to replace costly equipment or perform extensive maintenance.
• Minimize crashes or unexpected behavior from your system.
• Address known vulnerabilities to make it harder for attackers to exploit them.

It’s worth mentioning that vendors may focus their resources on providing support for newer products. Meaning that at some point, the systems you currently use will reach the end of their planned support period. When this happens, you can address this situation by:

• Exploring third-party solutions that provide additional layers of security.
• Evaluate other vendors that have similar solutions or buy the newest version of your product from your current vendor.
• Conduct regular security assessments to address any potential weaknesses (penetration test and scans).

#4. Intrusion Detection Systems (IDS)

An Intrusion Detection System is a software application that monitors your network and generates alerts when finding suspicious activity. There are two types of IDS:

• Signature-based IDS: It uses a database of known patterns of malicious activities (as signatures) and compares them to the observed traffic of your network. If it finds a match between the current traffic and the signature, it sends an alert to administrators because of a potential threat.
• Anomaly-based IDS: It uses a baseline of normal network behavior to compare against the current network. The baseline includes metrics like traffic volume, user behavior, and application usage. If there are any anomalies between the baseline and the current behavior of the network, the IDS sends an alert for suspicious behavior.

IDS is an invaluable SCADA security best practice as the logs and alerts can help with forensic analysis in the event of a security breach. Thanks to IDS you can:

• Detect potential threats and get information about their nature and severity.
• Prevent further damage or unauthorized access to other segments of your network.
• Take immediate action before any potential damage occurs.

#5. Security Audits and Assessments

A security audit in SCADA involves evaluating critical processes of your system. It often begins by identifying vital assets and access controls and then transitions to the review of policies, network architecture, and incident response plans.

Most security audits include simulated scenarios and penetration tests while checking that documentation complies with SCADA security standards like NIST and ISA/IEC 62443.

At the end of an audit, you get a comprehensive report with the vulnerabilities found as well as recommendations.

Some advantages of a SCADA security audit include:

• It opens up opportunities to provide training to employees and personnel who have access to or interact with the SCADA system.
• Getting accurate documentation related to security policies, incident reports, and other relevant records.
• Validation of security measures you already implemented or feedback for continuous improvement.

#6. Secure Communication Protocols

Secure communication protocols refer to a set of rules that control the exchange of information between devices or systems. It usually involves a combination of encryption, authentication, and cryptographic techniques to ensure that the data transmitted is confidential.

There are multiple communication protocols available, and the one that is right for you depends on factors like your specific industry, infrastructure, and regulations. For security in SCADA, the prevalent three protocols are:

• MQTT with TLS and client authentication: This is a communication protocol that coupled with Transport Layer Security (TLS) ensures the transmission of encrypted data. Also, adding an extra layer of security like client authentication makes MQTT the most secure protocol for SCADA systems.
• DNP3 (Distributed Network Protocol 3): This protocol is widely used in automation industries and it was specifically designed for SCADA systems. Modern DNP3 includes encryption and authentication and supports features like error checking, time synchronization, and data prioritization.
• Modbus with Security Extensions: Another widely used protocol in industrial automation. Modbus has a master-slave relationship where one master device (initiator) communicates with one or more “slave” devices (responder).

Thanks to these protocols you can:

• Prevent man-in-the-middle attacks that affect the communication between two parties.
• Ensure that data isn’t tampered with during the transmission and remains the same.
• Protect sensitive data from operational SCADA systems and ensure its confidentiality.

#7. Incident Response Planning

Incident response planning is a structured approach in which you categorize incidents by severity and craft response procedures that cover steps like detection, containment, eradication, recovery, and reporting.

Having an incident response plan is a crucial SCADA security best practice for several reasons:

• It allows an organized response and reduces the damage that results from an incident.
• It reduces downtime as a result of an unplanned event which ensures critical processes resume quickly.
• It ensures that you allocate resources efficiently in the case of an incident which optimizes your response efforts.

Encourage Continuous Monitoring

In the best-case scenario, it would be optimal to have all these technologies and methodologies in place. However, SCADA security best practices require an investment, whether that be money, time, or resources.

You can begin with the essentials: empower your team through training, foster awareness, maintain regular backups, and reinforce physical security measures. These foundational steps not only act as a way to fortify your security but also as a groundwork for more advanced features.

When it comes to security (and almost everything in life), every step, no matter how small, is still a step forward!