How can PLC and SCADA systems be updated and patched without compromising their availability and performance?

The first and most important thing is that a control network should always be physically isolated from the business network. There is no reason a PLC network needs to be accessible through the internet. If you want remote access, then there should be someone at the plant who is available to temporarily patch the PLC network into a public access network offering you a bridge. As far as updating the PLC, as in putting in a new system, there is no simple and easy way to do this. For large systems, your safest approach to avoid a downtime disaster is to build a second system in parallel and migrate equipment over one piece at a time. Once the entire plant has been moved over, then you can dismantle the old system.

Many times people jump in blindly and get themselves in trouble because they did not analyse impacts with a simple question: if i patch what happens? will my process go down? can i get out of this mess?

In an ICS environment, it is crucial to exercise caution with vulnerability scanners due to the potential risk of bricking PLCs. These devices are responsible for controlling critical operations, and any disruption to their functionality can have severe consequences. Approach vulnerability scanning in a controlled and well-planned manner, ensuring proper testing and validation processes are in place to mitigate the risk of unintentional damage. Ideally leverage ICS native protocols to gather data on installed firmware on PLCs. This approach allows for the collection of vital information about the system's firmware version and vulnerabilities while minimizing the potential for unintended consequences or disruption to the ICS environment.

Effective Redundancy in PLC/SCADA Updates Key to uninterrupted operations during updates is a robust redundancy system. A setup with primary and backup servers, extending to controllers, ensures smooth patching and reliability. Challenges exist in achieving full redundancy in industrial settings, but the effort significantly reduces update risks. Additionally, integrate regular backup testing, segmented network architecture, proactive monitoring, and employee training for comprehensive risk mitigation.

Updating and patching PLC and SCADA systems without compromising availability and performance requires a strategic approach. Implement a robust change management process to schedule updates during planned maintenance windows, minimizing operational impact. Use redundant systems and failover mechanisms to ensure continuous operation during updates. Thoroughly test patches in a controlled environment to identify potential issues before deployment. Employ incremental updates and rollback plans to swiftly revert changes if problems arise. Regularly back up system configurations and data to safeguard against update-related disruptions. This ensures seamless, secure, and efficient updates while maintaining system integrity and performance.

Having been in the business of dcs automation for almost 20 years planning and preparation is almost 80 percent of the battle but will validate ur procedure uncover a lot of problems in a controlled non stressful situation and give you time . Invest in a testing system this will pay 10 folds for itself.

There are many different approaches and vendors for this type of environment, but several years ago Gartner indicated that a simple, non-intrusive and low-friction way to understand if there is an attacker is the deception approach. It is very rare for administrators of these networks to allow the installation of traffic analysis tools, inline devices, additional security agents and even the application of patches. Very effective mechanism to have visibility of the environment and adding a control at network-level.

This again is in preparation. Talk to the users. Give operations and other stakeholders a heads up to do this during a non critical time so you have their support in case it’s does not go as planned and you can focus on troubleshooting versus answering nasty calls or emails.

It is unclear who the audience is - (IT or OT)? When you say talk to the users, who is talking to the users? Are you suggesting it is IT? Are you assuming IT has a firm grasp of OT OPS & Process Integrity, SCADA & DCS Apps, HMI's, Eng Programming WKST, Drives, MCC's, PLC's and their Architecture and ICS network design? Are you advocating IT / OT convergence?

Use of virtualization technologies to isolate the patching and updating process from the operational environment. By using virtual machines, updates and patches can be installed on a replica of the system, tested, and verified before they are implemented in the operational environment. This approach can significantly reduce the risk of any disruption to the operational environment, as the updates and patches are first tested in a controlled environment.

again this is in the planning phase. If you really know what you are doing you will know how to validate system health after implementation. Also in case of failure how you roll back.

Training is crucial and not only theory training but having a hands on training on a lab or test system is key so you can come as close as possible to the real production system.

A good procedure is a recipe you can give to anyone to carry out and have all the steps and details you require. A procedure also needs to be reviewed and updated to make sure it’s successful as system evolves so does procedures.

A robust VM program in an ICS environment starts with complete visibility across the system. This entails comprehensive asset identification and inventory, mapping network architecture, and understanding the software and hardware components used, including legacy and hidden ones, to ensure no blind spots exist. While air-gapping has been a traditional measure for protecting ICS equipment, it is not viable. Recent incidents have shown evidence of supply chain compromises and other sophisticated attacks that have successfully targeted air-gapped systems. A holistic VM approach is necessary, including continuous monitoring, threat intelligence, and timely patching, to safeguard the ICS environment effectively.

Updating PLC and SCADA Systems:- Scheduled Downtime- In a power plant, we scheduled updates during low-demand periods. This minimised impact on operations while ensuring system security. Staggered Updates- For a water treatment facility, updates were staggered across different PLCs, ensuring at least partial system availability at all times. Backup Systems- Implemented backup control systems in a manufacturing plant. While updating one system, the backup took over, maintaining uninterrupted operations. Virtual Testing - Before applying patches, we used virtual environments to test them, reducing risks of performance issues post-update.

There is never enough planning and preparation. Don’t be scared to make a solid plan to increase your chances of being successful.