Operational Technology (OT) environments -the industrial control systems (ICS), SCADA, PLCs, DCSs and embedded devices that run factories, utilities, transport and critical infrastructure -are no longer isolated appliances in a secure room. Increased connectivity, third-party integrations, remote access, and the broad adoption of IoT/IIoT have expanded attack surfaces dramatically. Adversaries (from cybercriminal ransomware gangs to nation-state actors) are actively targeting OT because successful disruption creates high leverage: financial extortion, geopolitical pressure, or physical disruption. Security frameworks like ISA/IEC-62443 and NIST guidance remain the baseline, but the threat landscape and practical exploitability continue to evolve fast.
Below are the 20 OT security risks CISOs need to prioritize in 2025 -written so you can brief executives, drive remediation plans, or build a roadmap.
Quick note on prioritization
Not every risk carries equal likelihood or impact for every asset. Use an exposure × criticality approach: start where internet-exposed + high-criticality meet, then address broad exposure and pervasive weaknesses. Recent vendor and research reports show internet-exposed OT devices and known-exploited vulnerabilities remain primary drivers of compromise.
The Top 20 OT Security Risks (with why they matter + mitigation)
1. Internet-exposed OT assets
Why: Devices with direct internet access are trivial targets for automated scanning and exploitation. Claroty and other industry reports repeatedly highlight insecurely exposed devices as a top exposure.
Mitigation: Inventory and block any unnecessary public exposures; use jump servers, VPNs with MFA, application gateways, and strong network segmentation.
2. Unpatched and end-of-life (EOL) OT software
Why: Patches for OT components are often delayed because of safety, availability, and vendor scheduling. Threat actors exploit known CVEs repeatedly via commodity tools. Mitigation: Compensating controls (network segmentation, virtual patching with IDS/IPS, compensating access controls) and a risk-based patch plan tied to asset criticality.
3. Weak or unmanaged remote access
Why: Remote vendor access and operator remote sessions are common. Misconfigured RDP, VPNs without MFA, and hardcoded credentials are regular root causes. Dragos and other vendors report secure remote access as a recurring finding
Mitigation: Zero Trust for OT (least privilege jump hosts, MFA, just-in-time access, session logging/recording).
4. Asset visibility gaps
Why: You cannot secure what you cannot see. Blind spots across legacy PLCs, field devices, and shadow IoT cause detection delays. Nozomi and Claroty show defenders still lack full visibility.
Mitigation: Continuous asset discovery, passive monitoring, and normalized OT asset inventory tied to CMDB.
5. Poor network segmentation and flat networks
Why: Flat or poorly enforced segmentation allows lateral movement from IT to OT and between OT zones – enabling small footholds to escalate into facility-wide incidents.
Mitigation: Apply IEC/ISA-62443 zone/conduit models, enforce rigorous east-west controls, and validate segmentation with red/blue tests.
6. Insecure protocols and legacy telemetry
Why: Many OT protocols (Modbus, OPC Classic, older DNP3 variants) lack authentication or encryption – making spoofing and replay practical.
Mitigation: Use protocol gateways, deep packet inspection for ICS protocols, and migrate to secured protocol versions where possible.
7. Third-party and supply-chain risks
Why: Third-party vendor access, outsourced maintenance, and supplier firmware introduce hidden vulnerabilities and credentials. Recent high-impact breaches in broader IT supply chains demonstrate that compromise of a supplier can cascade into OT
Mitigation: Enforce vendor onboarding, contract security SLAs, continuous monitoring of vendor sessions, and segmentation for vendor access.
8. Compromised credentials & identity drift
Why: Hardcoded credentials, shared operator accounts, and stale privileged accounts are frequent attack enablers.
Mitigation: Replace shared accounts with role-based identities, integrate PAM for OT, apply credential rotation and vaulting.
9. Ransomware and extortion targeting OT
Why: Ransom actors deliberately target industrial victims to increase pressure for payment. Ransomware remains a leading OT threat vector and often follows initial IT compromise. Nozomi and Dragos both flag ransomware persistence and evolution.
Mitigation: Immutable backups, air-gapped recovery plans, robust detection for pre-ransomware behavior, tabletop exercises.
10. Insufficient logging and detection in OT
Why: Many OT devices lack native logging or send logs to providers not integrated into SOC tooling, delaying detection.
Mitigation: Centralize logs (where possible), deploy passive packet/behavioral detection specific to ICS protocols, and tune SIEM for OT telemetry.
11. Unsafe change management & engineering practices
Why: Uncontrolled changes, emergency fixes, and bypassed safety controls create security weaknesses and can break safety-critical systems.
Mitigation: Formalize change control that balances safety and security, maintain baselines, and require peer review for engineering changes.
12. Insider risk and human error
Why: Operators or contractors with privileged access can unintentionally or maliciously create unsafe states.
Mitigation: Enforce least privilege, logging, periodic access reviews, and behavioral analytics where possible.
13. Asset sprawl from IIoT & OT/IT convergence
Why: Rapid deployment of sensors and IIoT devices increases attack surface and often bypasses procurement/security review.
Mitigation: Harden procurement policies, define secure onboarding flows and microsegmentation for new devices.
14. Lack of safety-informed security design
Why: Security controls must not compromise safety – but treating safety and security as separate silos frequently results in tradeoffs that cement vulnerabilities.
Mitigation: Cross-functional safety + security review boards, dual testing, and use of standards (IEC-62443) to unify requirements.
15. Vulnerabilities in vendor firmware and embedded code
Why: Firmware bugs and insecure default configs are exploited by attackers; firmware updates are often infrequent or incompatible with production windows.
Mitigation: Inventory firmware, require secure secure-by-design supplier commitments, and implement virtual patching where firmware updates are delayed.
16. Lack of OT incident response preparedness
Why: Responding to OT incidents requires unique playbooks that consider physical safety and process uptime – generic IT IR destroys trust and may cause hazards.
Mitigation: Develop OT-specific IR plans, run physical/operational playbooks and simulation drills with engineering and operators.
17. Inadequate physical security for critical OT assets
Why: Physical access to network ports, consoles, or devices can enable rapid compromise (USB malware, console access).
Mitigation: Harden physical access controls, tamper-evident seals, and monitor critical physical areas.
18. Misuse of AI/ML – both offense and brittle defenses
Why: AI will both help defenders (anomaly detection) and help adversaries (automated reconnaissance, faster exploit development). Nozomi and others predict AI/ML will play offensive and defensive roles in OT security.
Mitigation: Treat ML outputs as advisory, test models regularly, and combine signature/behavioral detection with human oversight.
19. Data exfiltration & espionage risks
Why: Even when disruption isn’t the goal, adversaries steal intellectual property, operational data, or engineering drawings – which can enable later attacks.
Mitigation: Monitor outbound flows, DLP for engineering systems, and segmentation between R&D and production networks.
20. Regulatory, compliance and insurance gaps
Why: Evolving regulation (critical infrastructure directives, national OT guidance) and insurer requirements increasingly push security obligations that organizations may not meet yet. Non-compliance can be costly.
Mitigation: Align to relevant standards (IEC/ISA 62443, NIST guidance), map controls to regulator expectations, and engage with legal/insurance early.
Practical roadmap: 90-day, 6-month, 12-month priorities
First 90 days (quick wins)
- Run an internet exposure sweep and close unnecessary public endpoints
- Inventory high-criticality assets (passive discovery).
- Lock down remote access: enforce MFA and JIT vendor sessions.
6 months
- Implement segmentation per zone/conduit model and validate via pen testing
- Deploy OT-aware detection (behavioral monitoring) and tie into SOC playbooks.
- Build vendor access program and credential vaulting.
12 months
- Formalize OT incident response with full tabletop exercises.
- Migrate critical systems off EOL software or implement validated compensating controls.
- Integrate OT metrics into board reporting (MTTR, mean time to detect, % internet-exposed).
How to brief the board – two slides that matter
- Risk snapshot: number of internet-exposed OT assets; % assets EOL; detection gap (hours). Use this to ask for budget for segmentation and visibility.
- Business impact story: tie an OT incident scenario (downtime, safety shutoff, regulatory fines) to potential revenue loss and remediation cost.
Tools, standards, and places to read next
- Dragos OT Year in Review – for active industrial threat group intel and incident trends.
- Claroty State of CPS Security – exposure mapping and device-level risk insights.
- Nozomi and other vendor trend pieces – practical detection & monitoring advice.
- CISA ICS resources and advisories – tactical advisories and coordinated vulnerability disclosure.
- ISA/IEC-62443 & NIST SP 800-82 – for governance and secure architecture guidance.
Final thoughts – the posture shift CISOs must make
OT security in 2025 is not a checkbox exercise. It’s a layered program that must simultaneously protect safety, operational continuity, and business resilience. The simplest mistakes – internet-exposed PLCs, unmanaged vendor access, stale credentials – still appear in incident postmortems and are among the highest ROI fixes you can make. Prioritize visibility and segmentation first, then invest in detection and response capabilities tailored to OT realities. Treat vendors and firmware supply chains as security problems, not procurement line items. And finally – practice: the people, processes and playbooks you exercise today are what keep the lights on tomorrow.