Critical infrastructure is increasingly becoming a prime target for cybercriminals and state-sponsored attackers. Whether it’s cyberattacks on utility networks, communication and transportation systems, government and healthcare institutions, or the banking and financial sector—successful attacks on CI can incur enormous costs and have devastating consequences for public safety. According to a recent report by the European Union Agency for Cybersecurity (ENISA), sectors such as public administration, healthcare, gas supply, and ICT service management in the EU still have significant security gaps. To defend against the growing number of attacks, CI operators require a multi-layered security approach that effectively strengthens their cyber resilience.
The Current Threat Landscape for Critical Infrastructure
There are numerous cyber threats aimed at critical infrastructure, seeking to cause massive operational disruptions, extort ransoms, or exfiltrate sensitive data. Amid rising global tensions, state-sponsored hacking groups are increasingly targeting CI to conduct espionage or disrupt essential services on which a country’s population depends. This enables hostile nations to undermine other states and create instability—while maintaining plausible deniability of their actions.
CI operators are also an attractive target for financially motivated cybercriminals. The likelihood of ransom payments being made is higher, as victims are often willing to do whatever it takes to restore their critical systems.
While common threats like ransomware and phishing remain widespread, attackers have shifted their tactics in recent years and are increasingly focusing on file-based malware to target CI operators. Other attack strategies include the use of botnets, exploitation of zero-day vulnerabilities, and deployment of Advanced Persistent Threats (APTs).
These attackers aim to maximize the impact of their attacks. Although assaults on CI organizations typically begin in IT networks, criminals often shift their focus to operational technology (OT), where they can cause significant disruptions. The complex and highly interconnected nature of CI network infrastructures further increases the risk. Weaknesses in one area can cascade into broader, systemic failures—making robust cybersecurity measures essential.
Security Challenges for CI Operators
Security teams face several challenges that hinder their ability to effectively counter the threats facing CI operators. One of the first hurdles is that security strategies require executive approval. Often, there is a gap between the security team’s plans and the resources and budgets that are actually approved. Despite the growing number of threats, cybersecurity budgets remain stagnant or are being cut. These financial constraints force security teams to focus on only the most urgent risks, leaving them poorly prepared to address new attack tactics and methods.
In addition to limited budgets, evolving environments place further strain on security teams. In the past, IT and OT systems were managed as separate environments with dedicated teams. In recent years, however, the convergence of IT and OT has led to security teams being tasked with managing systems with which they may have little or no experience.
For example, CI organizations often integrate SCADA systems used for remote access and telemetry collection with standard IT networks. This integration has expanded the attack surface and increased the expertise and resources needed for effective defense. A lack of in-depth IT and OT knowledge leads to a gap in understanding how IT threats can affect OT systems—and the broader consequences of such threats. Due to a shortage of trained cybersecurity professionals, teams struggle with the complexity of hybrid environments, which include cloud storage, open-source tools, and connected platforms.
In light of these challenges and the increasing sophistication of cyber threats, implementing a multi-layered security strategy—such as a defense-in-depth approach—is crucial.
Multi-Layered Security: A Defense-in-Depth Approach for CI
Defense-in-Depth is a multi-layered security concept designed to reduce reliance on a single point of failure. By integrating multiple security controls, this approach helps close security gaps, reduce the risk of compromise, improve threat detection when traditional protections are bypassed, and accelerate incident response. Additionally, it neutralizes malicious content and effectively identifies anomalies. Organizations should tailor their defense-in-depth strategies to prioritize the protection of critical assets essential for uninterrupted operations.
The first line of defense includes network security controls such as firewalls, gateways, and data diodes to regulate traffic and prevent unauthorized access or data exfiltration. Network segmentation adds another layer of protection by isolating threats and ensuring that an incident in one area doesn’t compromise the entire system.
Equally important is data security, which reduces the risk of file-based malware. Multi-scanning technologies integrated into network appliances clean or block malicious content in files before they reach sensitive systems. These technologies can detect and block known malware with extremely high success rates—over 99%. Previously unknown threats can be identified through advanced sandboxing and threat intelligence that detects known threat actors and their infrastructure.
With modern technologies such as Deep Content Disarm and Reconstruction (CDR), files can be thoroughly sanitized of malicious code. These clean files are stored in isolated data vaults to ensure only fully inspected data enters OT networks, preserving their integrity.
Endpoint protection forms another key security layer, safeguarding devices like laptops and desktops that are common targets for attacks via removable media. Comprehensive endpoint solutions combine multiple malware detection engines, behavioral analysis, and threat intelligence feeds to combat both known and zero-day threats.
Email security tools that block phishing attempts and scan attachments or URLs for malicious content are also essential for reducing risk and improving an organization’s overall cyber resilience.
Together, these interconnected layers form a robust and comprehensive defense to protect systems and prevent damage from cyberattacks. By adopting a multi-layered approach, CI operators can build a resilient cybersecurity framework that effectively protects their most critical assets against increasingly sophisticated and far-reaching threats.