Digital Security of Critical Infrastructure

Critical infrastructure refers to the comprehensive set of physical and digital systems, assets, and networks that operate in mutual interdependence and are indispensable for a country’s economic stability, social order, public health, and national security. These infrastructures encompass essential service domains such as energy production and distribution facilities, water and waste management systems, transportation networks, healthcare providers, financial institutions, and communication infrastructure.

With the acceleration of digital transformation, a significant portion of these systems has become integrated with information technologies, enabling major advancements in operational efficiency and decision-making processes through applications such as remote monitoring, automation, and data analytics. However, this digitization process has also introduced new security risks. The increasing vulnerability of critical infrastructure to cyber threats has heightened the likelihood of malicious actors interfering with industrial control systems, data flows, or service networks.

Such attacks or disruptions can lead not only to the cessation of economic activities but also to the impairment of public services, the emergence of social unrest, and the weakening of national security. Situations such as the interruption of energy supply, contamination of water resources, or the collapse of health information systems can result in both short-term crises and long-term loss of public confidence in infrastructure.

For these reasons, the digital security of critical infrastructure holds a central place in national cyber defense strategies. Policies are being developed to strengthen information sharing, standardization, and coordination among public institutions, the private sector, and international organizations; threat detection, incident response, resilience planning, and risk management processes are continuously being improved. Digital security is now regarded not merely as a technological requirement but as a fundamental element of national sovereignty and social sustainability.

Key Infrastructure Sectors

Critical infrastructure constitutes a broad framework encompassing the essential services and systems necessary for the continuity and stability of a society. These infrastructures play a central role in ensuring the uninterrupted operation of economic activities, public services, and national security. Each country determines its critical infrastructure sectors according to its own socio-economic structure, geographic conditions, and strategic priorities. However, in general terms, sectors such as energy, communications, transportation, healthcare, and finance are universally recognized as common priorities.

In the United States, the Cybersecurity and Infrastructure Security Agency (CISA) has defined 16 essential critical infrastructure sectors. This classification includes energy, financial services, transportation systems, health and public health, information technology, defense industry, water and wastewater systems, communications, critical manufacturing, emergency services, and food. This approach aims to shape national security strategies within a holistic framework by taking into account the interdependencies among different sectors.

In Türkiye, under Law No. 7545 on Cybersecurity and related secondary regulations, the main sectors designated as critical infrastructure are classified as follows:

• Energy: Electricity generation, transmission, and distribution networks; oil and natural gas pipelines; nuclear facilities and energy storage systems.
• Information and Communication Technologies: Telecommunication infrastructure, internet service providers, data centers, satellite communications, and cloud computing services.
• Finance and Banking: Banks, stock exchanges and other financial markets, electronic payment systems, and digital currency infrastructure.
• Transportation: Air, land, sea, and rail transport; ports, airports, metro systems, and intelligent transportation networks.
• Healthcare: Hospitals, laboratories, pharmaceutical and medical equipment supply chains, biotechnology institutions, and health insurance systems.
• Water Management: Drinking water supply and distribution systems, treatment plants, dams, wastewater infrastructure, and water quality monitoring networks.
• Public Services: Emergency services (firefighting, police, ambulance), public administration buildings, and national security-related facilities.
• Critical Production and Industry: Defense industry facilities, chemical, automotive, electronics, and heavy industrial plants using industrial control systems (ICS/SCADA).
• Food and Agriculture: Food production, processing, storage, and distribution networks; agricultural supply chains and livestock infrastructure.

Each of these sectors is critically important not only within its own domain but also for the security and continuity of other infrastructures. Therefore, international standardization initiatives, risk analysis methods, and cybersecurity protocols are gaining increasing importance. Protecting critical infrastructure has become a strategic necessity for sustaining both national resilience and social well-being.

Cyber Threats to Critical Infrastructure

The rapid digitization of critical infrastructure and its interconnection through information systems have expanded its attack surface, rendering it more vulnerable to various cyber threats. This situation has elevated vital sectors such as energy, healthcare, transportation, finance, and water management to high-risk targets not only from a technical perspective but also from a national security standpoint. Today, cyberattacks targeting critical infrastructure manifest as complex actions carried out by states, organized crime groups, ideologically motivated individuals, or insiders with differing motivations.

Threat Actors

State-Sponsored Actors (APT Groups)

These groups, known as Advanced Persistent Threats (APTs), are typically supported directly or indirectly by states. Their primary objectives are to conduct political, military, or economic espionage or to weaken the infrastructure of rival nations. APT groups establish persistence by infiltrating target systems over extended periods and employing advanced techniques such as sophisticated malware, reconnaissance methods, and zero-day vulnerabilities.

Cybercriminals

Driven by financial gain, these groups engage in activities such as ransomware deployment, data theft, fraud, and the illegal sale of access credentials. They can disrupt the operational continuity of critical infrastructure to pressure victims into paying ransoms. In recent years, the proliferation of cryptocurrency has made tracking such attacks more difficult and contributed to the growth of the criminal economy.

Hacktivists

Hacktivist groups, acting to convey political or ideological messages, typically aim to generate public attention through service disruptions (defacement, DDoS) or data leaks. While these attacks may not cause direct economic damage, they can damage the reputation of government institutions or private companies and undermine public trust.

Insider Threats

Threats arising from individuals employed within critical infrastructure organizations or granted access to these systems. These threats may result from intentional sabotage, data leakage, or negligence and carelessness. Detecting insider threats is more challenging than detecting external attacks because these individuals possess authorized access to systems.

Attack Types and Methods

Ransomware

Attackers encrypt data and block access using malicious software introduced into infrastructure systems, demanding a ransom for restoration of access. In 2021, a ransomware attack on the U.S.-based Colonial Pipeline company disrupted fuel supply chains nationwide, highlighting the national-level importance of cybersecurity for critical infrastructure. ^【1】

Denial-of-Service (DDoS) Attacks

Excessive traffic is directed at networks and systems to prevent legitimate users from accessing services. These attacks target high-traffic systems such as financial institutions, government portals, and communication infrastructure. DDoS attacks are often used as a diversionary tactic to support other cyber operations.

Attacks on Industrial Control Systems (ICS/SCADA)

Operational Technology (OT) systems monitor and manage physical processes in digital environments. Attacks on these systems, used in environments such as energy production plants, water treatment centers, or production lines, can cause physical equipment damage, service interruptions, and environmental risks. The Stuxnet malware, discovered in 2010, demonstrated the real-world impact of such attacks by disrupting Iran’s nuclear centrifuges. ^【2】 Additionally, legacy protocols commonly used in ICS systems, such as Modbus and DNP3, remain highly vulnerable due to the absence of encryption or authentication support.

Supply Chain Attacks

In these attacks, the target is not the infrastructure system itself but third-party software, hardware, or service providers used by the system. Attackers exploit these intermediary connections to gain access to the primary target’s systems. The SolarWinds incident in 2020 was one of the most comprehensive supply chain attacks, simultaneously affecting numerous government agencies and private organizations. ^【3】

Social Engineering and Phishing

These attack types exploit human error rather than technological defenses. Attackers obtain login credentials or access data from employees through fake emails, websites, or phone calls. In critical infrastructure operations, these seemingly simple attacks often serve as the initial entry point for more complex cyber operations.

These threats to critical infrastructure demonstrate that cybersecurity measures must be supported not only by technological tools but also by corporate awareness, staff training, risk management, and international cooperation. In this context, cybersecurity has become both a technical and strategic national security issue.

Potential Consequences and Risk Areas of Cyber Attacks

A successful cyberattack on critical infrastructure can produce wide-ranging effects that extend beyond technical systems to impact economic, social, environmental, and national security dimensions. These impacts can manifest in interconnected chains, where a disruption in one sector directly affects the functioning of other infrastructures. The primary risk types resulting from such attacks can be classified as follows:

Operational Risk

Disruptions in essential services such as electricity, water, transportation, healthcare, or communications directly affect daily life and economic activities. Such disruptions can halt production processes, break energy supply chains, or paralyze transportation networks. Operational risks can also limit the capacity of public institutions to respond to emergencies.

Security Risk

Targeting control systems used in critical infrastructure—such as traffic signalization, air traffic management, medical devices, or hospital information systems—can lead to direct threats to human life. Such attacks may cause accidents resulting in physical harm or even fatalities among workers or citizens.

Environmental Risk

Compromising the control of environmentally sensitive infrastructure such as chemical production facilities, nuclear power plants, or water treatment systems can lead to the release of toxic or radioactive substances into the environment. This can contaminate soil, water sources, and ecosystems, resulting in long-term threats to public health and biodiversity.

Financial Risk

Cyberattacks can cause direct revenue losses, contractual breaches, and delays in supply chains due to service disruptions. Additionally, data breaches or service interruptions may trigger legal liabilities, compensation claims, regulatory fines, and increased insurance premiums, further increasing financial burdens. In the long term, such incidents can permanently damage institutional reputation and erode investor confidence.

National Security Risk

The failure of critical infrastructure can render a society unable to meet its basic needs—food, water, energy, and healthcare. This situation can lead to public panic, breakdown of public order, and economic instability. Furthermore, targeting military communication systems, defense industry facilities, or border security infrastructure can weaken a nation’s defense capabilities and deterrence posture.

These multidimensional risks transform critical infrastructure security from a mere technical cybersecurity issue into a domain requiring strategic-level national attention. An effective protection approach demands a comprehensive risk management framework integrating technological safeguards with institutional preparedness, emergency management, regulatory compliance, and international cooperation.

Cybersecurity Strategies and Measures

The complex, dynamic, and interdependent nature of critical infrastructure necessitates a multi-layered, integrated, and proactive security approach in an environment where single-layer defenses are insufficient. This approach requires a holistic strategy encompassing technical, operational, managerial, and legal dimensions. Security measures at every level must not only prevent current threats but also aim for early detection, rapid response, and sustainable recovery capabilities against potential attacks.

Risk Assessment and Management

The foundation of an effective cybersecurity strategy lies in the systematic evaluation and management of risks. This process includes inventorying critical assets, analyzing the functional importance and vulnerability level of each asset, identifying threat vectors, and modeling potential attack scenarios. The risk management cycle is not a one-time analysis but a dynamic process continuously updated in parallel with system updates, infrastructure changes, and evolving threat landscapes.

Technical Security Measures

Network Security and Segmentation

Physically or logically separating Information Technology (IT) and Operational Technology (OT) systems makes it harder for attackers to move from one network to another. Dividing networks hosting critical systems into smaller sub-segments (micro-segmentation) limits the impact of potential attacks. This structure is supported by firewalls, intrusion detection and prevention systems (IDS/IPS), network monitoring tools, and Zero Trust architecture.

Access Control and Identity Management

Authorization mechanisms must be configured according to the “principle of least privilege.” Each user should have only the minimum level of access necessary to perform their duties. Multi-Factor Authentication (MFA) and continuous authentication systems are fundamental tools for preventing unauthorized access.

Vulnerability Management and Penetration Testing

Regular scanning of systems, timely software updates, and prompt patching of identified vulnerabilities reduce the risk of attackers exploiting known weaknesses. Penetration testing and red team exercises measure the resilience of defense mechanisms against real-world attack scenarios.

Data Encryption and Backup

Critical data must be protected using strong encryption algorithms both at rest and in transit. Backup processes must not only prevent data loss but also include plans for rapid system restoration following ransomware attacks. Backups should be stored in geographically separated secure environments and regularly tested for integrity.

Operational and Managerial Measures

Staff Training and Awareness

The weakest link in critical infrastructure is often not the technical systems but the human factor. Therefore, employees must be regularly trained on social engineering, phishing, password security, mobile device usage, and data privacy. Establishing a “cybersecurity culture” across the organization is a fundamental element supporting technical defenses.

Emergency and Disaster Recovery Plans

Ensuring operational continuity during attacks or failures requires pre-defined crisis scenarios and emergency response plans. These plans encompass incident response, business continuity, disaster recovery, and communication management processes. The effectiveness of these plans must be tested through regular drills.

Public-Private Sector Collaboration

Since a significant portion of critical infrastructure is operated by the private sector, information sharing, threat intelligence exchange, and coordinated response efforts between public institutions and private organizations are of great importance. National cybersecurity centers, sector-specific information sharing platforms (ISACs), and joint exercises institutionalize this collaboration.

Critical Infrastructure Security and Legal Regulations in Türkiye

Türkiye has become a major target for cyber threats in recent years due to its geostrategic position and the rapid pace of its digital transformation. The digitization of critical infrastructure sectors such as energy, finance, transportation, and public services has positioned the country as a strategic digital hub regionally; this has simultaneously expanded the attack surface and increased cybersecurity risks. In this context, a comprehensive institutional and legal framework has been initiated to establish a unified national cybersecurity policy and strengthen inter-institutional coordination.

Institutional Structure and New Law

For many years, Türkiye’s cybersecurity ecosystem was fragmented across the jurisdictions of various institutions and units. Within this framework, the Ministry of Transport and Infrastructure, the Information and Communication Technologies Authority (BTK), and its subsidiary, the National Cyber Incident Response Center (USOM), played key roles in implementing national cybersecurity strategies and responding to incidents. USOM coordinates with Cyber Incident Response Teams (SOME) within public institutions and private organizations to conduct national-level threat intelligence sharing and attack detection activities.

However, this structure, characterized by overlapping responsibilities and a limited legal framework, required a more centralized and holistic regulatory approach. As a result, Law No. 7545 on Cybersecurity entered into force in 2025, introducing a new administrative structure for the determination, implementation, and oversight of strategic cybersecurity policies in Türkiye. ^【4】

Under this law, the Presidency of Cybersecurity has been established as a central authority with the power to formulate policy, coordinate, monitor, and enforce sanctions at the national level in combating cyber threats. The Presidency is responsible for defining national cybersecurity strategies, establishing standards for the protection of critical infrastructure, and regulating inter-institutional information sharing.

Responsibilities of Critical Infrastructure Operators

Law No. 7545 imposes various technical and administrative obligations on critical infrastructure operators and institutions active in the field of cybersecurity. The primary aim of these obligations is to enhance national cybersecurity resilience, ensure rapid incident detection, and promote the use of domestic technologies. Key obligations include:

• Information Sharing: All requested information, documents, log records, and technical data must be provided to the Presidency in a timely manner.
• Incident Reporting: Critical infrastructure operators are obligated to report any detected cybersecurity incidents and system vulnerabilities to the Presidency without delay.
• Compliance with Inspections: Operators must grant access for on-site or remote technical inspections conducted by the Presidency.
• Use of Domestic and National Products: The use of domestically developed and nationally approved technologies is mandatory for cybersecurity products, hardware, and software solutions.

Violations of these obligations are subject to severe penalties under the law, including substantial administrative fines, suspension of operations, and, in certain cases, imprisonment.

This new legal and institutional framework is regarded as a pivotal milestone in Türkiye’s pursuit of national sovereignty, digital independence, and critical infrastructure resilience in the field of cybersecurity. The law also aims to strengthen Türkiye’s role in the global cyber resilience network by establishing a framework aligned with international cybersecurity norms.

Future Perspectives and Emerging Technologies

The threat landscape for critical infrastructure security is evolving dynamically alongside technological advancements and becoming increasingly complex. The proliferation of digital systems, increased automation, and integration of artificial intelligence-based technologies enhance infrastructure efficiency while simultaneously creating new attack vectors. Future threats are expected to challenge existing defense mechanisms and necessitate the development of new security paradigms.

Potential Future Threats

AI-Enabled Autonomous Attacks

Artificial Intelligence (AI) technologies are increasingly being used not only in defense systems but also by attackers. Advanced algorithms can autonomously identify system vulnerabilities and develop evasion strategies to bypass defenses. Such attacks can be executed at high speed and with precise targeting without human intervention, significantly complicating detection and response processes.

Exploitation via Internet of Things (IoT) Devices

IoT components used in critical infrastructure—such as sensors, smart meters, industrial control modules, and remote access devices—often have limited security measures. Attacks through these devices can create backdoors into infrastructure networks. Large-scale botnet networks (e.g., similar to Mirai) can leverage these devices to enhance the effectiveness of DDoS attacks.

Misuse of 5G Infrastructure

5G technology plays a fundamental role in industrial automation, autonomous vehicles, and smart city infrastructure due to its high data transfer speeds and low latency. However, its virtualized and software-defined architecture creates new targets for cyberattacks. Compromising 5G core network components or edge computing nodes could simultaneously disrupt numerous services.

Quantum Computers and Cryptographic Breakthroughs

With the advancement of quantum computing, widely used asymmetric encryption algorithms such as RSA and ECC (Elliptic Curve Cryptography) will become vulnerable to decryption. This also introduces the risk that previously encrypted data could be decrypted in the future. Therefore, the transition of critical infrastructure to “post-quantum” cryptographic systems is inevitable.

Evolving Defense Technologies and Approaches

AI and Machine Learning-Enabled Defense Systems

Artificial intelligence and machine learning provide speed and scalability advantages beyond human capability in threat detection. These technologies can identify anomalies in network traffic, unusual user behavior, or internal system inconsistencies in real time, enabling automation of detection and response processes while reducing false positive rates.

Blockchain-Based Security Applications

Blockchain technology holds significant potential for critical infrastructure due to its decentralized nature, ensuring data integrity and secure record sharing. Particularly in energy markets, supply chain management, and digital identity verification, blockchain can enhance trust by enabling immutable data recording.

Adoption of Zero Trust Architecture

The Zero Trust model eliminates the traditional assumption that “internal networks are trusted.” In this approach, every access request, regardless of origin, must undergo authentication and authorization. This model provides an effective strategy for preventing insider threats and lateral movement (an attacker’s horizontal progression within a system), especially in complex and distributed infrastructures.

The Importance of Continuous Adaptation

The future cyber threat environment demands systems that continuously learn, evolve, and rely on threat intelligence rather than static security solutions. Consequently, critical infrastructure security has moved beyond being a static protective activity; it has become a dynamic process integrating technology, policy, human resources, and international cooperation.

Continuous adaptation is not only essential for countering new attack methods but also for ensuring the sustainability of security policies. In this context, the development of AI-supported defense mechanisms, quantum-resistant cryptographic techniques, and nationally coordinated cybersecurity strategies is regarded as the key to protecting future critical infrastructure.