ThreatSTOP Blog

Safeguarding the “Unprotectable”: Shielding Agentless SCADA and IoT Devices

Written by Joel Esler | May 26, 2025

Industrial control systems, smart-city infrastructure, and remote IoT sensors keep the modern world humming, but most of these devices were never built for today’s threat landscape. They run proprietary firmware, lack the horsepower for agents, and often sit in locations where rolling a truck is impractical. Traditionally they’ve been labeled “unprotectable.”

ThreatSTOP turns that assumption on its head.

Why Agentless SCADA/IoT Security Is Hard … and Urgent

 

Challenge

Impact on OT / IoT Security

Legacy protocols & minimal resources

Firmware can’t run AV or EDR agents.

Remote, widely‐distributed sites

No staff on-site to patch or monitor.

Always-on operations

Downtime for retrofits is unacceptable.

High-value targets

Ransomware or nation-state actors see an easy pivot into critical infrastructure.

 

With attackers focusing on DNS- and IP-based command-and-control, blocking bad lookups before they ever reach the device is the fastest, least-disruptive way to cut the kill-chain.

ThreatSTOP’s Product Line: Protection Without Retrofits

 

Product

How It Protects Agentless Devices

Ideal OT / IoT Use Cases

DNS Defense Cloud(cloud-hosted recursive resolvers)

• Instant protective DNS—just point remote sites at ThreatSTOP’s anycast resolvers.
• Thousands of threat-intel feeds (3rd-party + organic) updated every 60 sec.
• No hardware to deploy; perfect for field equipment with limited connectivity.

Wind or solar farms, highway signage, satellite uplinks, kiosks in retail chains.

DNS Defense(on-prem caching resolver package)

• Deploys on existing on-site DNS servers or lightweight VMs.
• Enforces ThreatSTOP policies locally, even when the WAN is down.
• Granular, per-zone policies for mixed IT/OT networks.

Manufacturing plants, water treatment facilities, substations that require local resolution.

IP Defense(firewall & router block-list automation)

• Pushes curated block lists to any IP-based control point—NGFW, router, ICS gateway, or SD-WAN edge.
• Ideal where SCADA devices speak raw TCP/UDP but not DNS.

Modbus/TCP controllers, building-automation BACnet routers, L2-segmented IoT VLANS.

 

Case-Study Spotlight – Water Utility 

When Southern California’s South Coast Water District upgraded its cyber-defenses, it chose ThreatSTOP’s full stack—IP Defense, DNS Defense, Roaming Defense, SIEM integration, and API access. Without touching a single PLC or pump-station controller, SCWD now blocks thousands of malicious domains and IPs each month and has cut mean time-to-detect/respond by over 40 percent.

Some Secret Sauce: ThreatSTOP’s Feedback Loop

Our Security, Intelligence & Research team ingests telemetry from customers worldwide, pivots on newly blocked activity, and adds fresh indicators—in many cases convicting malicious IPs or domains months before large-scale abuse begins (e.g., 173.0.146.175 and its 165 phishing domains). That continuous “Feedback Loop” means SCADA and IoT fleets inherit protections automatically, with zero extra work.

A Zero-Trust, Network-First Architecture

  1. Protective DNS at the Edge – Malicious domains never resolve, neutering phishing kits and malware downloads on bandwidth-constrained links.

  2. Policy-Driven IP Blocking – Even protocols that bypass DNS are stopped cold at the firewall or router.

  3. Micro-segmentation – Simplified ACLs ensure PLCs, sensors, and HMIs talk only to approved services.

  4. Real-Time Anomaly Alerts – ThreatSTOP correlates policy hits with global threat intel, so SecOps can act before an incident escalates.

All of this happens without installing code on fragile devices or forcing risky firmware upgrades.

Proof in the Field

  • Water-district SCADA network: Five integrated ThreatSTOP solutions protect OT & IT, slashing incident response time by 40 % and automating block-list updates across pump stations and treatment plants. 

Business Value

  • Speed to Protection – Minutes, not months; flip a DNS setting or import a block list.

  • No Capital Expense – Leverage what you already have: DNS resolvers, routers, or firewalls.

  • Operational Resilience – Policies update automatically; no downtime, no truck rolls.

  • Regulatory Alignment – Helps meet NIST CSF, IEC 62443, TSA pipeline, and other OT security frameworks.

  • Return on Investment - SCWD reports eliminating new hardware costs and reducing manual rule-maintenance while keeping critical water services online.

     

Next Steps

Ready to make your “unprotectable” devices Protected-by-ThreatSTOP?

  • Request a Pricing Quote – Email sales@threatstop.com or visit threatstop.com.

  • Talk to an Engineer – Our team can map a rollout that fits your network realities.

  • Jump into a free Demo - Sign up for a Demo for our cloud product, free for 30 days.

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