Network Segmentation: Definition and Best Practices

2020 was not a good year for cybersecurity. In the first half of that year alone, ransomware (a special kind of malware) attacks increased by 715 percent from the prior year’s levels.

A global survey found that 57 percent of organizations experienced a phishing attack, up from 55 percent in 2019, while the average total data breach cost climbed to $3.86 million.

To mitigate the risks of such cyberattacks, enterprises need to do more. One tactic proven to help is implementing network segmentation practices.

What are “network segments,” and how can a segmented network improve cybersecurity? Today’s post answers those questions. We’ll also unpack five network segmentation best practices to help boost your enterprise network’s security.

What Is Network Segmentation?

Network segmentation divides an enterprise network into smaller segments or sub-networks with limited interconnectivity.

Segmenting networks gives administrators better control over network traffic as that traffic flows from one segment to the next and improves your ability to prevent unauthorized users from accessing the organization’s devices, applications, and data.

And if a data breach does happen — which, let’s not delude ourselves, can always occur — network segmentation assures that the breach only affects that targeted segment. The other network segments remain protected from further damage.

How Can Network Segmentation Improve Security?

In the enterprise network, firewalls and other protective mechanisms cannot permanently block or detect threats within the organization’s network. Segmentation can prevent more cyberattacks, reduce damage, and improve overall network performance.

One reason is that segmenting improves access control, so only authorized users with specific privileges can access each segment.

This means that even if an attacker does gain access to one segment, they won’t be able to access the rest of the network; the attacker can only move around within whatever segment the stolen access credentials allow. This helps to minimize damage and prevents the network from failing in its entirety.

By implementing network segmentation best practices, you also get better visibility into and control over network traffic so that you can minimize any threats to your systems — both external and internal.

Remember, securing the computer network from internal threats is now just as important as securing it from external threats. This is because the earlier “trust assumption” — where insiders were assumed to be trustworthy and not a threat — has eroded.

Perhaps the insiders have ill intent; they’re unwitting dupes in a criminal scheme; possibly, attackers have stolen their credentials to impersonate the insider. Regardless, the insider can be a source of data breaches just as much as an outsider.

Adopting Zero Trust Architecture (ZTA) is essential, and network segmentation is part of the ZTA approach. You can create a micro perimeter around your most critical assets to protect them from unauthorized users and bad actors.

Segmented architecture also helps to simplify firewall security policies. You can further reduce your attack surface by using a consolidated policy for subnet access control (as well as threat detection and mitigation).

Micro-segmentation (implemented through software-defined networking) can also allow you to enforce more granular security policies to meet your organization’s specific cyber-defense needs.

Segmenting reduces regulatory compliance costs by limiting the number of systems that fall within the scope of a compliance audit.

Other Benefits of Network Segmentation

In addition to strengthening your security posture, network segmentation provides other advantages that improve network operations and management.

Segmenting your network by department, function, or application allows you to optimize traffic flow based on usage patterns. This eliminates congestion and bottlenecks, ensuring critical applications get the required bandwidth and priority.

Additionally, network segmentation enhances troubleshooting capabilities. Issues can be isolated to a specific segment without impacting the rest of the network. You gain visibility into exactly where performance problems or faults are occurring.

Network segmentation enables you to scale parts of your infrastructure independently as needed. Traffic growth in one department won’t necessarily require upgrades for the whole network.

By taking a strategic approach to network segmentation that maps to your business functions, you gain security, flexibility, scalability, and manageability – critical pillars for the digital enterprise.

Main Goals of Network Segmentation

Network segmentation’s primary goal is to improve overall cybersecurity by preventing lateral movement of threats and prospective attackers within the network.

A breach in one portion of a classic flat network, where all devices and systems are part of a single domain, might provide attackers access to critical resources throughout the network infrastructure.

Network segmentation reduces this risk by erecting barriers between segments, limiting the attacker’s access to a specific zone during an attack.

Network Segmentation vs. Micro-Segmentation

Network segmentation and micro-segmentation are related strategic concepts for securing your infrastructure, but some key differences exist.

Network segmentation divides your network into subnetworks based on function, department, geography, or other logical separations. This creates security boundaries to restrict lateral movement and isolate malware and other threats infiltrating the internal network. Segmentation is typically enforced at the subnet level using Virtual Local Area Networks (VLANs), Access Control Lists (ACLs), firewalls, and security zones.

Micro-segmentation furthers this concept by enabling more granular isolations at the subnet level and even down to the individual workload, container, endpoint, or virtual machine. Rather than just traditional network gear, software-defined perimeters and Zero Trust Network Access (ZTNA) enforce secure boundaries between micro-segments.

Examples of Network Segmentation

Organizations can segment their corporate network environment in various ways to improve security and meet business needs. Here are three common examples:

• Segment by Department: Dividing your network based on departments (finance, sales, HR, etc.) allows you to customize access and security controls based on data sensitivity and level of trust. For example, external guest access can be isolated from internal resources.
• Segment Application Tiers: Grouping application components like web servers, databases, and APIs into dedicated tiers or security zones helps minimize impacts and vulnerabilities from threats targeting a specific part of the stack.
• Isolate BYOD: Allowing personal and BYOD devices their network segment lets you enable access while limiting lateral connectivity to business-critical systems not intended for remote access. Distinct policies can be applied.

Network segmentation aligns access and security controls to trust levels, functionality, and data criticality. This provides in-depth defense against threats that infiltrate the internal network.

How Can You Segment a Network?

Network segmentation can be implemented as either logical or physical segmentation. Physical segmentation involves segmenting a more extensive network into smaller segments using physical or virtual firewalls.

Logical segmentation creates subnets with Virtual Local Area Networks (VLANs) or network addressing schemes. It requires no wiring or the physical movement of components, making it more flexible and automation-friendly.

Network segmentation can be done through firewall segmentation at specific network boundaries. The firewall provides visibility into network traffic and can be set to allow/block various kinds of traffic, applications, and users.

If your organization aims for PCI-DSS compliance, consider PCI DSS network segmentation to isolate and protect credit card data from other computing processes.

Eight Network Segmentation Best Practices

1. Understand who accesses what.

Proper network segmentation starts by first knowing who can access the network and who should access which parts of the network — and that might not always be the same group of people.

By defining access needs clearly, you can ensure no issues requiring a costly and time-consuming re-architecture of the segmentation process might arise later.

2. Avoid Under or Over-Segmentation.

One of the most essential network segmentation best practices is to create the correct number of segments to balance security with complexity.

Too many segments will make it harder to control and manage the network. Too few will weaken the network’s security profile.

3. Restrict and Control Third-Party Access.

Bad actors can attack your enterprise network or data center through third-party vendors or suppliers.

The risk of third-party data breaches is not only on the rise; it can also cost organizations about $370,000 more than if a third party was not involved. Restricting third-party access to your critical systems and sensitive data is essential.

Creating separate portals to serve each vendor will isolate and limit an attack, even if it happens.

4. Consolidate Similar Network Resources.

Combining similar network resources into individual databases is another network segmentation best practice to follow. With such a tactic, you can quickly implement information security controls and ensure that business-critical data remains isolated and protected.

5. Perform Network Audits.

Regular and comprehensive network audits, with risk assessments and penetration testing, are critical to avoiding bad actors trying to exploit your enterprise network in many ways.

By auditing the network, you can find exploitable gaps and take action to close them before a bad actor has a chance to slip in and cause damage. Audits will also reveal if your previous network segmentation plan needs to be updated.

6. Assess your Assets Value.

Organizations should inventory their assets and assign valuations before initiating network segmentation activities. Each asset, from Internet of Things (IoT) devices to databases, should be classified according to its relevance and data sensitivity.

Separating things of lesser and higher value while retaining a complete inventory of business assets facilitates the transition and execution of a network segmentation plan.

7. Implement Endpoint Protection Measure.

Hackers frequently target endpoint devices because they are frequently unprotected and lack sufficient safeguards. A single compromised device can provide hackers with access to the whole leading network.

Endpoint Detection And Response (EDR) technology helps enterprises add an extra layer of security by proactively monitoring Indications Of Attack (IOAs) and Indications Of Compromise (IOCs).

8. Follow the Principle of Least Privilege.

Once network segmentation is in place, each network should adhere to the zero-trust paradigm and the concept of least privilege. These practices entail restricting network access at every level, which demands authentication and verification from all parties within the network boundaries, both internal and external, before getting access to additional areas of the network.

Network administrators may immediately detect malicious actors or unauthorized parties attempting to breach the network using Zero Trust Architecture (ZTA). Only authorized users with the appropriate permissions can access the data on that network.

How ZenGRC Can Supplement Network Segmentation

The modern cyber threat landscape is teeming with bad actors looking for ways to attack your enterprise network. To stay ahead of them, you must take action today.

Protect your network, vulnerable devices, endpoints, and data with a robust network segmentation strategy. And get it right by adhering to this article’s network segmentation best practices.

You can strengthen your organization’s security posture, but this requires taking action — sooner rather than later.

Implementing a robust cybersecurity strategy can be daunting, mainly if your organization is responsible for adhering to cybersecurity compliance frameworks.

ZenGRC is a risk management and compliance solution that can supply compliance and cybersecurity teams with a centralized, integrated dashboard that identifies risk across your organization.

ZenGRC simplifies risk management and provides complete views of your control environments, easy access to your documentation at audit time, and continuous monitoring of your security stance over time.

To learn more about ZenGRC and how it can support your compliance and network security strategy, contact us now for a free demo.