Why Microsegmentation Is the Most Practical Form of Virtual Patching

In an ideal world, every cybersecurity vulnerability could be patched immediately.But in real industrial environments, “cannot be updated” is often the norm—not the exception.

Across semiconductor equipment, medical devices, industrial control systems, and critical infrastructure, there are vast numbers of EOS / EOL (End of Support / End of Life) devices still operating in production lines and clinical settings.These systems remain mission-critical, yet no longer receive security updates from vendors.

When vulnerabilities cannot be physically patched, what options remain?The answer is Virtual Patching.

What Is Virtual Patching?

Virtual Patch does not fix source code or update operating systems.Instead, it blocks attack paths before vulnerabilities can be exploited.

Simply put:

The vulnerability still exists — but the attacker cannot reach it.

Virtual Patching is commonly applied when:

• Legacy devices cannot be updated

• Updates require downtime that disrupts production or clinical operations

• Certified systems must not be modified

• Vendors have not yet released official patches

In these situations, Virtual Patch is not a workaround — it is the only viable risk-mitigation strategy.

Why Traditional Virtual Patching Falls Short

Historically, Virtual Patching relied on:

• Perimeter firewalls

• IPS / WAF rules

• Signature-based blocking

  
  

However, these approaches reveal serious limitations in modern environments:

• Perimeter-only protection: Once attackers enter the internal network, lateral movement remains possible

• High maintenance cost: Manual rule updates must track evolving vulnerabilities and exploits

• Limited behavioral awareness: Difficulty distinguishing normal vs. abnormal device communication

In reality, the most critical risks occur within internal device-to-device communication.

Microsegmentation: Shifting from "Fixing Vulnerabilities" to "Controlling Behavior"

Microsegmentation introduces a fundamentally different mindset.Instead of asking “How do we fix this vulnerability?”, it asks:“Who should this device actually be communicating with?”

The core principle of microsegmentation is simple:Treat every device as its own security zone, allowing only explicitly authorized communications and denying everything else.

This makes microsegmentation the most effective and practical implementation of Virtual Patching.

How Microsegmentation Becomes the Most Practical Virtual Patch

1. Directly Cuts Attack Paths

   Even if a vulnerability exists, it cannot be exploited if communication with the attack source is blocked.

2. Prevents Lateral Movement

   A compromised device cannot be used as a pivot point to attack other critical systems.

3. Requires No Device Modification

   No OS updates, no agents, no configuration changes — ideal for:

   • Semiconductor equipment

   • Medical devices

   • Industrial control systems and critical infrastructure

4. Remains Effective for EOS / EOL Devices

   Device lifecycles far exceed software support timelines.Microsegmentation ensures that legacy does not automatically mean high risk.

Why Regulations Are Converging on the Same Requirement

Whether it is:

• SEMI E187 (semiconductor equipment cybersecurity)

• FDA Cybersecurity Guidance (medical devices)

• EU Cyber Resilience Act (CRA)

All emphasize the same core principles:

• Restrict unnecessary network communication

• Prevent devices from becoming internal attack pivots

• Require mitigation measures when immediate patching is not possible

Microsegmentation is the technical control that best satisfies these requirements.

Janus Perspective: AI-Driven Microsegmentation Eliminates Manual Virtual Patching

The biggest challenge with traditional microsegmentation is not technology — it is operational burden.

• A single device may have dozens or hundreds of legitimate communication flows

• Maintenance or version updates frequently change behavior

• Manually creating and maintaining allowlists is unsustainable

  
  

Janus netKeeper was designed to solve exactly this problem:

• AI automatically learns normal device behavior

• Communication allowlists are generated and continuously updated

• Unknown or anomalous traffic is blocked in real time

• Agentless, OS-independent architecture

• Full support for EOS / EOL environments

With Janus, microsegmentation becomes a continuously operating Virtual Patch, not a one-time configuration.

Conclusion: When Physical Patching Fails, Microsegmentation Is the Answer

In the world of product security and critical infrastructure,not every vulnerability can be patched — but every risk must be managed.

Microsegmentation provides a pragmatic approach:

• Stop chasing individual vulnerabilities

• Ensure vulnerabilities cannot be exploited

  
  

That is the true essence of Virtual Patching —

and why microsegmentation has become indispensable in modern product cybersecurity.