What Is Network Segmentation?

Benefits of Network Segmentation

Whatever schema an organization uses, a segmented network has some clear advantages over a flat network with no hierarchy or subnets. These benefits include:

• Stronger cybersecurity for sensitive data: This benefit encompasses breach prevention (north-south movement), tighter access control, and security controls specific to each segment.
• Less difficulty meeting regulatory compliance requirements: Limiting who can access certain data and where it flows simplifies compliance attestation and audits for industry and government regulations like PCI DSS and GDPR.
• Simpler risk analysis and damage control: When cybercriminals can’t move freely around your entire network, it’s easier to pinpoint their techniques and identify weaknesses in your security posture.
• Safer endpoints and users: This goes both ways—end users and devices are safer on a segmented network where threats can’t easily spread to endpoints, and the segments themselves are safer from threats that begin at the endpoint.
• Reduced network congestion: Activity in one segment won’t throttle it in another part of the network. For instance, in a retail store, customers using guest Wi-Fi won’t slow down credit card transactions.

Network Segmentation Best Practices

To help you learn the right way to implement and maintain an effective network segmentation model, here are five network segmentation best practices to live by:

1. Don’t over-segment

Many organizations over-segment their networks when they first start out. Doing so can decrease your overall network visibility and make management even more difficult than before you began segmenting. However, it’s also important not to under-segment your network, as this keeps your attack surface broad and hurts your security posture.

2. Perform regular audits

Network segmentation is an excellent way to improve your network security, but it’s only effective when you continually check in to see that vulnerabilities are closed off, permissions are tight, and updates are installed. Most of all, auditing your segments ensures there are no exploitable gaps in coverage and that any network risks are mitigated—keeping you one step ahead of relentless bad actors.

3. Follow the principle of least privilege

Least-privileged access can make or break access management in general, and it’s no less crucial when it comes to network segmentation. By applying the principle of least privilege across all your network segments, you guarantee your users, network admins, and security team that access is only granted when necessary. This is why least-privileged access is fundamental for zero trust network access.

4. Limit third-party access

Granting access to third-party users already comes with high risk, so it’s important to grant such access only where it’s needed, especially if you’re granting it to a variety of network segments. Segmentation reduces overall risk to your network, but that doesn’t mean you should begin doling out permissions to third parties without considering how it could affect your network security posture.

5. Automate where you can

Segmenting your network grants your organization a bevy of valuable opportunities to automate. Besides the given benefits of automation in general—such as increased visibility, reduced MTTR, and improved security—automating network segmentation allows you to quickly identify and classify new assets and data, which is another segmentation best practice in itself.

Disadvantages of Traditional Segmentation

What we can’t overlook is that in today’s complex network architectures—distributed as they are across multiple clouds and data centers—the old firewall and VLAN models of segmentation have some major shortcomings.

Traditional firewalls have a key flaw that directly opposes segmentation: they create flat networks that allow easy lateral movement. Trying to compensate for this is so operationally burdensome and complex that it’s almost impossible. Even next-generation firewalls, with all their added capabilities, still put users on your network to access applications. VLANs have the same weakness.

A traditional approach leaves you dealing with:

• Excessive trust: Because traditional firewall-based segmentation is designed to prevent attacks from outside, it can leave you vulnerable to insider threats.
• Misconfigurations: VLANs are easy to misconfigure in today’s architectures, especially if you use third-party cloud providers and can’t change the infrastructure yourself.
• Work-intensive management: Every new app, device, or change means updating firewall rules, and even mundane activities like vulnerability scanning require more resources.
• Complex controls: Traditional methods lack fine-grained controls, making it complicated to define segmentation policy for remote workers, partners, customers, and so on.
• Scalability issues: To handle network growth, you need to create smaller segments or upgrade existing ones, resulting in higher costs to scale and maintain.
• Poor performance: Adding more network devices (e.g., firewalls, routers) has a compounding negative effect on your overall network performance.