How can you secure legacy control systems that were not designed with cybersecurity in mind?

The initial risk assessment is crucial, but real value comes from understanding specific context of your legacy systems & how they interact with modern networks. Utilizing NIST or ISA/IEC standards is just the start. Delve deeper, consider unique operational & business constraints. Layer defenses (defense in depth), is crucial & involves network segmentation to isolate control systems, ensuring only necessary communication is allowed. Employing strong access controls & monitoring for unusual activity are vital. Training personnel to recognize & respond to potential security threats is invaluable. Consider establishing a relationship with vendors for updates & support, even for older systems. The best strategy is often a phased approach.

It’s always a great idea to keep your machinery control networks seperate to any wan connected networks. Stuxnet showed just how critical it is to keep your process closed to the outside world

Implementation of control systems security should begin by considering multiple aspects and I will note few here. 1. Gathering detailed inventory of the hardware or software components is crucial to begin the process 2. Perform details risk assessment for the vulnerabilities and find out the possible impact of those vulnerabilities 3. After the assessment, as per the company guidelines, need to take decision whether we need to remediate vulnerabilities or access the consequences of vulnerabilities.

Risk Assessment: Conduct regular risk assessments to identify potential vulnerabilities and prioritize remediation efforts based on the level of risk. Securing legacy control systems is an ongoing process, and a combination of these measures can help improve their cybersecurity posture. Regularly reassess the security landscape and adjust strategies accordingly.

The approach: 1- Recognize the unique vulnerabilities of these systems. 2- Implementing robust network segmentation is crucial; isolate these systems from broader networks to limit potential breach impacts. 3- Regularly update security protocols and software, balancing stability with protection. 4- Focus on human factors: train staff in cybersecurity awareness and establish strict access controls. 5- Consider gradual system upgrades, replacing outdated components with more secure, modern alternatives.

Agree Isolating Critical Assets, Segmentation creates virtual barriers that separate LCS from other less critical network segments, including IT systems or administrative networks. This restricts the attack surface, making it harder for attackers to reach and target crucial systems. If a breach occurs in one segment, it's contained within that zone, preventing lateral movement and potential disruption to critical operations. Also to Enhanced Visibility and Control, traffic monitoring is by breaking down the network into smaller segments, it becomes easier to monitor traffic flow and identify suspicious activity. This allows for early detection of intrusions or anomalies, enabling faster response and mitigation measures.

Isolating control systems from untrusted networks is vital. Using firewalls & routers to create separate security zones allows for more granular control over who & what can access systems. This isn't just about blocking external threats, it's also about controlling internal traffic to minimize potential damage from any breach. Implementing VLANs or VPNs can further enhance security, especially for remote access scenarios. It's crucial to regularly update & monitor these tools to ensure they're effectively guarding against new threats. Understanding the flow of data & how systems interact is important. Tailor your segmentation strategy to reflect the operational realities & needs of your system. Segmentation isn't a set-&-forget solution.

Here is the key. Because of the nature and purpose of the technology applied to plant are different, different purposes need different networks. Some o them are naturally secure but the most will require specific barriers. Some networks can be logical (virtual) but some need to be optically separated.

This is a great control to mitigate risks if the system gets compromised and prevent risks to other critical systems or even the whole environment.

Network Monitoring: Implement continuous network monitoring to detect unusual or malicious activities. Use intrusion detection and prevention systems to identify and respond to potential threats. Access Controls:

And here in comes the LI article written by someone (or AI) that does not understand the subject matter. Most legacy systems (key word legacy) can't be patched or fixed which is why there are issues in securing them. Upgrading and replacing isn't straightforward either and often unaffordable. Needs to wait for a refresh cycle (10, 15, 25 years anyone?) All this focus on an asset or endpoints when we should consider how we can protect upstream from the asset without need to touch the asset itself. This can be done at the network level or with Industrial protocol aware specialist solutions and/or things like virtual patching.

Regularly patch and update legacy system software and firmware with the latest security fixes. Collaborate and reach out to OEM/vendor for patching outdated systems, Legacy system may require support or alternative solutions.

As already stated, updating legacy PLC / control systems is in most cases NOT possible. You need to "protect" the device with a secure gateway before it in the network. A secure gateway can be also a modern industrial controller with high security standards based on IEC62433 and a software app for firewall.

Adhering to best practices & standards is crucial. Follow industry-specific guidelines from associations, regulatory bodies, & vendors to maintain system integrity & security. This includes regular updates, patch management, & strict access controls. Training staff in cybersecurity awareness is essential and they should understand potential threats & the importance of following security protocols. Enforce strict policies for system access & usage, & regularly review these policies to adapt to new threats. This approach fortifies your system against attacks & fosters a culture of security within your organization, making every team member a vigilant defender of your critical infrastructure.

Access Control and Monitoring: 1. Strong Authentication: Implement authentication for all control system access. Avoid weak passwords and change default credentials. 2.Principle of Least Privilege: Grant users only the minimum access required for their specific tasks. Limit administrator privileges and monitor their activity. 3.Log Monitoring: Monitor system logs for suspicious activity, including unauthorized access attempts, configuration changes, and error messages.

Schwachstellen müssen abgesichert werden. Menschliches Verhalten der Nutzer ?Mensch“ und deren Bewusstseinsbildung sind ein wichtiger Aspekt für die IT-Sicherheit, weil oft mangelndes Vorstellungsverm?gen besteht, was Verfehlungen oder Nachl?ssigkeiten für Auswirkungen der Systemsicherheit bewirken k?nnen. Schulungsma?nahmen und die Einschr?nkung der Eingriffsm?glichkeiten mit automatisierer Kontrolle sind geeignete Ma?nahmen.

Simple and quick: change the standard password of the industrial controller, which is in many cases just the brandname for user and password!

Beyond deploying defenses & tools, it's crucial to adopt a proactive & adaptive security posture. Regularly conduct penetration testing & vulnerability assessments to identify & remediate weaknesses before attackers exploit them. Engage in threat hunting activities to detect hidden threats. Establish a robust incident response plan, ensuring you're prepared to quickly contain & recover from any breaches. Consider benefits of collaborating with industry peers & gov entities to share threat intelligence, staying ahead of emerging risks. Securing legacy systems is an ongoing journey requiring continuous improvement & vigilance. The landscape evolves, so must strategies, ensuring control systems remain resilient against ever-changing threats.

Bei Leitrechnern in Automatisierungssystemen werden Daten und Befehle zwischen dem Leitsystem und der Steuerung ausgetauscht (Anlagenfunktionen, z.B. das Schalten von Antrieben etc. und das übertragen von Parametern an die Steuerungssysteme) sowie Rückgemeldungen zum Betriebszustand. Werden dazu reservierte Speicherbereiche genutzt und die Kommunikation auf reine Zahlenwerte eingeschr?nkt, k?nnen Schadprogramme aus Steuerungssystem selbst ferngehalten werden. Auch über IoT Ger?te eingeschleppte Schadprogramme werden unwirksam, wenn diese auf Zahlenwerte transformiert werden. Der so gefilterte Datenverkehr setzt valide Daten und damit in der Software implementierte Prüfmechanismen voraus.

The recovery plan must cover all parts of the system under consideration. For example, even if a PLC isn't itself compromised, an attack that causes a power outage can leave a PLC without code & retentives if the PLC's battery backup is old. In this case do you have a current PLC code backup, the cable required to connect to the PLC to program it, the PC software required to program the PLC, a software licence required to use the PLC programming software, an OS that supports the PLC programming software, a suitably aware user who can operate the programming system + recommission & any passwords required. There is a tendency to concentrate on Windows boxes in situations like this but the entire system requires consideration.

Well, lets see what the process needs to do - since its different for a watercompany versus an oio and gas company . Are we talking about proces comtrol, historian data , engineering net working stations , proactive monitoring or data collection real time or near time? Are there remote connectivity areas with open networks is there a a FAT SAT procedure in place. This makes your approach viable for standardization according to NIST ISA 99 and ofcourse TripleDefence #Tripled the next level in cyberdefence the followup of #TripleA better known as zero trust..

Develop a OT Cyber Incident Response Plan: 1. Prepare for potential cyberattacks with a documented response plan according to infrastructure. 2. Clearly Define roles, responsibilities, and communication procedures. 3. Conduct regular table top & incident response exercises.

This is the most important part. If you can managed to have a proper recovery plan and provide it resources for it to work then you will be in a good position to implement the other steps as well. Prevention is one thing but the ability to restore will keep your business going.

First: check that you have a back of the control system; Second: store is safe; Third: implement a process for regular backups.

Securing legacy control systems may includes isolating them from the internet, updating software and deploy recommended patches, implementing firewalls & data diode, monitoring network traffic, and conducting regular risk assessments to identify vulnerabilities, weaknesses and threats.

Based on my experience, I recommend developing a migration plan to replace the legacy control system device when the budget allows. However, it may not be possible if the control system was developed as one-of-a-kind to produce unique patented parts. In this case, the options for securing the control system are limited to isolating the system in a secured location and monitoring the physical access control system and CCTV. If the legacy control system runs software on an EoL/EoS operating system (e.g., Windows 3.1/95/2000/XP/7), virtualizing the OS and Engineering Software on the system in Hypervisor may be possible. Also allows for the hardening of the virtual server and adding a virtual security appliance for monitoring.

It’s not impossible and sometimes there is no alternative, but it is expensive. You need to add the security controls around the current system. For example transparent threat detection and mitigation in the IP network layer, isolation and abstraction of UI (desktop virtualisation) and isolation of the vulnerable system. It’s very important you have a lab where, having identified and implemented these compensating control, they can be rigorously tested for effectiveness.

Consider Physical Security: Protect control systems from physical tampering and unauthorized access. Implement physical access controls, surveillance systems, and environmental safeguards.

Is important to consider to use compensative measures. Secure end points, secure networks, implement monitoring tools. Environment hardening, should include engineering station. Create policies to manage movile and other electronic devices , such as usb, drives, laptops, phones, test devices etc. Physical access and safeguard controls. Visitor screening and so.