Table of contents
- Why OT cyber security matters in data centers
- The IT/OT convergence and the new attack surface
- Five best practices for OT protection in data centers
- Technical focus: how a BMS works in a data center
- Practical example: monitoring OT devices with Python
- The future of OT resilience
Data centers represent the backbone of services, platforms, and applications that support everyday life and global business. Every click, every transaction, every interaction passes through these infrastructures, where millions of data points are processed, stored, and distributed. Yet while traditional cyber security has focused for years on the IT world, another, quieter but equally vital layer is drawing increasing attention from experts and cybercriminals alike: OT cyber security, the protection of operational technology.
OT cyber security in data centers is now a critical issue because these environments, in addition to servers and IT networks, also host systems that manage electrical power, cooling, air conditioning, physical security, automatic doors, and environmental sensors. All of these elements are governed by a complex ecosystem known as the Building Management System (BMS).
It is precisely this layer once separate and isolated that has now become a prime target for cyber-physical attacks.
As IT and OT continue to converge, protection can no longer be treated as two separate worlds. Operational continuity, data security, and infrastructure stability depend on the ability to manage both in a coordinated way, through an integrated and dynamic approach.
The aim of this deep dive is to provide a clear, concrete, and practical view of how to protect OT systems in data centers, through five fundamental best practices and tools that can be readily adopted even by internal technical teams.
Why OT cyber security matters in data centers
Data centers demand continuous operation 24 hours a day, 365 days a year. Even a short interruption can translate into significant financial loss or service disruption.
The dual challenge is to maintain high performance and simultaneously defend against increasingly sophisticated threats.
OT (Operational Technology) systems were designed to ensure efficiency, automation, and physical control of plants and infrastructure. However, their initial design rarely took cyber security into account. Many devices still in use in BMSs rely on legacy software, unencrypted protocols, and access interfaces without strong authentication. In some cases, these systems are connected to the Internet to allow remote control, creating a direct entry point to critical infrastructure components.
A successful attack on a BMS can have dramatic consequences.
Example
An attacker who compromises a building’s climate control system could disable rack cooling, causing a data center to overheat within minutes. They could also tamper with fire sensors, trigger false alarms, or block emergency power systems, leading to large-scale service interruptions.
According to multiple industry analyses, over 70% of industrial automation and BMS systems have at least one known vulnerability that could be exploited to gain unauthorized access or install malware. In some cases, attackers are not seeking direct damage but rather using OT infrastructure as a foothold to move laterally into the IT network, where sensitive data and corporate servers reside.
This dynamic makes OT cyber security no longer a niche concern, but a central element of an organization’s overall security strategy.
The IT/OT convergence and the new attack surface
For decades, IT (Information Technology) and OT (Operational Technology) were treated as separate worlds. IT managed data, applications and networks; OT controlled physical processes, sensors and automation. Today, the divide is dissolving. Modern data centers integrate both domains: environmental sensors feed server-room control software, climate systems communicate across networks, and remote-maintenance portals connect OT controllers to external technicians.
This IT/OT convergence brings tremendous efficiency, but also an expanded attack surface.
What was once isolated now uses TCP/IP connectivity, web interfaces, cloud-based dashboards and REST APIs. A vulnerability in a BMS controller can become an entry point into the corporate network or worse, into other parts of the physical infrastructure.
Consider a major European data center that experienced a 12-hour outage in 2024 after an attacker deployed a ransomware payload not on the IT servers, but on the energy-supervision system.
The attacker exploited an unsecured remote-maintenance account, encrypted configuration files for the BMS and forced manual intervention.
The estimated financial impact exceeded 4 million EUR. This illustrates that the perimeter of risk is no longer purely digital; it is both physical and operational.
Five best practices for OT protection in data centers
Managing OT cyber security means navigating a complex landscape where physical infrastructures, industrial software, and network connections converge. To effectively protect a data center, it’s essential to adopt a structured approach based on five key pillars: asset inventory, network segmentation, secure remote access, threat detection, and exposure management.
Let’s look at each of them from a practical perspective.
1. Asset Inventory: know what you must protect
The first step in any OT defense strategy is knowing exactly what you need to protect.
Many attacks succeed not because hackers are smarter than defenders, but because organizations lack full visibility into their systems.
An asset inventory helps create an accurate map of all devices connected to the data center’s OT network: HVAC controllers, UPS units, temperature sensors, fire protection systems, network equipment, communication gateways, and industrial IoT devices.
In such a heterogeneous environment, using automated asset discovery tools can make a real difference. These tools passively analyze network traffic, identifying devices, protocols, and services without disrupting system operations.
Example
In a medium-to-large data center, an automated analysis might reveal dozens of unknown or misconfigured devices: a router with outdated firmware, a sensor connected with default credentials, or an unencrypted Modbus module. Every “shadow” in the network represents a potential entry point for an attack.
2. Network segmentation: isolate to limit damage
Once the assets are identified, the next step is to divide the network into logical and physical segments.
Network segmentation is one of the most effective techniques for preventing lateral movement by an attacker.
In a modern data center, BMS systems should be isolated from the IT network through dedicated VLANs, perimeter firewalls, and strict access rules.
In practice, this means that an administrative server should never be able to communicate directly with a cooling unit controller unless there is a specific operational need and active monitoring in place.
A good approach is to apply the “zero trust” model to OT as well: every connection must be explicitly authorized, authenticated, and verified.
Segmentation reduces the impact of a potential compromise: if a sensor is infected, it cannot propagate malware to the entire system.
Many data centers today adopt “cellular” architectures, where each OT zone (for example, the HVAC system) has its own separate network segment with centrally managed access controls.
This not only improves security but also simplifies maintenance and diagnostics.
3. Secure Remote Access: protect the entry points
Maintenance and remote monitoring operations are essential, but they also represent one of the main vulnerability points.
Many OT attacks start with unsecured remote access: weak credentials, shared VPNs, or forgotten accounts.
To reduce this risk, it is essential to implement a secure remote access policy based on three key principles:
- Multi-Factor Authentication (MFA)
Mandatory for every external user or technician. - Least Privilege
Grant access only to the systems and for the duration strictly necessary. - Monitoring and Logging
Every remote session must be tracked, with centralized logs for audits and forensic analysis.
Some data centers use “jump host” or “bastion host” solutions, which act as an intermediate point between the external network and the OT network.
This way, remote access never connects directly to critical devices but always passes through a secure, controlled node.
4. Threat Detection: see it before you need to fix it
A secure OT system is not just protected it’s aware.
Real-time monitoring of traffic and anomalous behavior is one of the most effective defenses against attacks.
In an OT environment, however, it’s not enough to apply the same tools used in IT. Detection algorithms must be contextualized: they need to recognize that an out-of-hours Modbus command or a sudden HVAC controller reset is a suspicious event.
The goal is to create a proactive detection system capable of:
- Identifying network anomalies
- Flagging deviations in physical parameters (temperature, energy consumption, pressure)
- Correlating events between the digital and physical worlds
Example
If a temperature sensor reports abnormal values while a suspicious login occurs on a controller at the same time, the system should automatically generate an alert.
5. Exposure management: prioritize real risk
Not all vulnerabilities are created equal. Some, even if technically severe, may have minimal impact; others, seemingly minor, can bring an entire infrastructure to a halt.
Exposure management aims to identify and remediate the vulnerabilities that pose the greatest threat to operational continuity.
In the OT world, where updates cannot be freely installed, prioritization becomes even more critical.
Rather than focusing solely on patch management, it’s essential to develop a risk-prioritization approach: protect critical systems first those controlling power or HVAC and only then address secondary devices.
An effective approach combines automated analysis with human evaluation. OT vulnerability assessment tools map firmware versions and configurations, but it is the security team that decides the order of intervention based on criticality and business impact.
Technical focus: how a BMS works in a data center
The Building Management System (BMS) is the operational brain of a data center.
Through a network of sensors and controllers, the BMS oversees all physical systems: HVAC (Heating, Ventilation, and Air Conditioning), electrical power, uninterruptible power supplies (UPS), lighting, access control, and fire safety systems.
Each component communicates with a central controller using protocols such as Modbus, BACnet, or SNMP, transmitting environmental and operational data.
The controller aggregates this information and sends it to supervisory servers, where it is displayed on graphical interfaces for technical staff.
Under normal conditions, the BMS operates autonomously, adjusting temperature and energy consumption to optimize server performance.
However, if a malicious actor compromises the system, they could manipulate real physical parameters: turning off cooling, stopping fans, simulating false alarms, or even altering safety thresholds.
This is why the BMS is considered a critical attack surface and must be treated like a high-sensitivity IT system, with strong authentication, encryption, and continuous monitoring.
Practical example: monitoring OT devices with Python
Below is a simple Python script you can use as a basis for monitoring OT devices on your network. When integrated into a broader system with logging, dashboards and alerts, it supports foundational visibility for OT defense.
import socket
import time
devices = {
"HVAC_Controller": "192.168.10.21",
"UPS_System": "192.168.10.35",
"Fire_Sensor": "192.168.10.48"
}
def check_device(ip, port=502, timeout=3):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(timeout)
try:
s.connect((ip, port))
print(f"[OK] Connection active with {ip}")
except Exception as e:
print(f"[ALERT] Device {ip} unreachable: {e}")
finally:
s.close()
while True:
print("\n--- Scanning devices ---")
for name, ip in devices.items():
print(f"Checking {name} ({ip})...")
check_device(ip)
time.sleep(300) # repeats every 5 minutesThis code cyclically checks the status of the specified OT devices and generates an alert if a node does not respond.
In a real-world context, the system can be integrated with centralized logging modules, graphical dashboards, and notifications via email or API, providing a simple yet effective foundation for OT visibility.
The future of OT resilience
Protection of OT in data centers is not a destination it’s a continuous journey.
As infrastructures become more automated and interconnected, the complexity of the security perimeter grows. The key challenge is not just “stopping attacks,” but reducing exposure, anticipating vulnerabilities and ensuring operational resilience even when compromise occurs.
Today, the trend is moving toward full integration between IT and OT monitoring.
Advanced security systems no longer just observe logs or network traffic they correlate physical and digital data: an unusual voltage drop can be analyzed alongside a suspicious remote login, and a temperature fluctuation can trigger checks on configuration files.
OT cyber security thus becomes a discipline of balance: between technology and process, prevention and response, centralized control and local autonomy.
The most mature organizations understand that defense is not built solely with firewalls or antivirus software, but with visibility, training, and a culture of security.
Conclusion
In an era dominated by artificial intelligence and advanced digitalization, data centers are the beating heart of a connected society.
Defending OT infrastructure means protecting not just the servers, but also the vital fabric that keeps the entire digital ecosystem alive.
The five best practices asset inventory, segmentation, secure access, detection, and risk management are not just technical measures; they are an operational philosophy.
Every organization should adopt them as daily habits, integrating them into governance models and maintenance processes.
Ultimately, OT cyber security is a strategic investment. It is not only about preventing incidents, but about building trust and continuity in a world where every bit and every sensor matters.
Those who can combine security, efficiency, and an integrated vision will be ready to manage the next generation of resilient data centers.
Frequently asked questions
- What is OT cyber security?
It refers to the practices and technologies designed to protect physical-process and control systems (such as BMS, HVAC, UPS) from cyber threats. - How does it differ from IT security?
IT security focuses on protecting data and networks; OT security protects devices and processes that interface with the physical world. - Why is it important in data centers?
Because an attack on OT systems can disable power, cooling or physical safety mechanisms causing critical service interruptions. - What are the most common threats?
Unauthorized access, ransomware, exploitation of unencrypted industrial protocols and remote-maintenance vulnerabilities. - How can an organization start protecting OT?
By creating an asset inventory, segmenting the network and enforcing secure access with strong authentication. - What tools are used for OT monitoring?
Passive network sensors, integrated SIEM platforms, behaviorual-analysis engines and OT-specific anomaly-detection systems. - Can legacy OT systems be updated?
Not always, but risks can be mitigated through dedicated firewalls, intermediary proxies and network segmentation. - How should remote access to OT systems be managed?
Via secure VPNs, multi-factor authentication and full session logging and auditing. - How important is staff training?
It is essential: the human factor often remains the weakest link; awareness strengthens resilience. - What is the future direction of OT cyber security?
Towards AI-driven adaptive protection and real-time integration of physical and digital event correlation.
