As we have discussed in earlier blogs, network segmentation is the practice of splitting computer networks into subnets using combinations of firewalls, VLANs, access controls and policies & procedures. We have seen that the primary reason for segmenting networks is to prevent a simple perimeter breach from exposing the totality of an organization’s information assets. So what is the difference between network segmentation and network enclaving?

One of the differences is just the degree of segmentation you impose upon the network. Enclaves are more thoroughly segmented from the general network environment than usual. In fact, enclaving is sometimes just described as “enhanced network segmentation.”

Another difference between segmentation and enclaving is the primary threat enclaving strives to thwart: the internal threat. Although the preponderance of cyber-attacks come from external threat sources such as hackers, cyber-criminals and nation states, many of the most devastating breaches originate from internal sources such as employees and trusted service providers. These internal information security breaches may be either purposeful attacks or may simply be caused by employee error. Either way, they are just as devastating to an organization’s reputation and business share.

A rarely considered difference between enclaving and network segmentation is physical security. When fully controlling access to information assets based on the principle of need to know, it is not enough to just control logical access. It is necessary to restrict physical access to work areas and computer devices as well. These areas should be locked, and access by authorized personnel should be recorded and monitored. Visitors and service providers should be pre-approved and escorted when in protected areas.

An obvious problem with enclaving is that it is more difficult to implement and maintain than the usual information security measures. It requires more planning, more devices and more employee hours. So why should businesses trying to control expenditures put their resources into enclaving?

As an information security professional I would say that it should be done because it is the best way we know to protect information assets. But for many business concerns, the greatest benefit of true enclaving is in securing protected and regulated information such as payment card information, patient health records and personal financial information. If you employ enclaving to protect such assets, you are showing clients and regulators alike that your business is serious about securing the information in its charge. And in today’s business climate, that can be a very important differentiator indeed!

If you look at most cutting-edge network information security guidance, job #1 can be paraphrased as “Know Thy Network.” It is firmly recommended (and in much regulatory guidance demanded) that organizations keep up-to-date inventories of hardware and software assets present on their computer networks. In fact, the most current recommendation is that organizations utilize software suites that not only keep track of inventories, but monitor all critical network entities with the aim of detecting any hardware or software applications that should not be there.

Another part of network knowledge is mapping data flows and trust relationships on networks, and mapping which business entities use which IT resources and information. For this knowledge, I like to go to my favorite risk management tool: the Business Impact Analysis (BIA). In this process, input comes from personnel across the enterprise detailing what they do, how they do it, what resources they need, what input they need, what output they produce and more (see MSI blog archives for more information about BIA and what it can do for your information security program).

About now, you are probably asking what all this has to do with network segmentation. The answer is that you simply must know where all your network assets are, who needs access to them and how they move before you can segment the network intelligently and effectively. It can all be summed up with one phrase: Need to Know. Need to know is the very basis of access control, and access control is what network segmentation is all about. You do not want anyone on your network to “see” information assets that they do not need to see in order to properly perform their business functions. And by the same token, you do not want network personnel to be cut off from information assets that they do need to perform their jobs. These are the reasons network knowledge and network segmentation go hand-in-hand.

Proper network knowledge becomes even more important when you take the next step in network segmentation: enclaving. I will discuss segmentation versus enclaving in my next blog later this month.

Network segmentation is the practice of splitting your computer network into subnetworks or network segments (also known as zoning). This is typically done using combinations of firewalls, VLANs, access controls and policies & procedures. Implementing network segmentation requires planning and effort, and it can entail some teething problems along the way as well. So why should it be done?

The number one reason is to protect the security of your network resources and information. When people first started to defend their homes and enterprises from attack, they built perimeter walls and made sure everything important was inside of those walls. They figured doing this would keep their enemies outside where they couldn’t possibly do any damage. This was a great idea, but unfortunately it had problems in the real world.

People found that the enemy only had to make one small hole in their perimeter defenses to be able to get at all of their valuables. They also realized that their perimeter defense didn’t stop evil insiders from wreaking havoc on their valuables. To deal with these problems, people started to add additional layers of protection inside of their outer walls. They walled off enclaves inside the outer defenses and added locks and guards to their individual buildings to thwart attacks.

This same situation exists now in the world of network protection. As network security assessors and advisors, we see that most networks we deal with are still “flat;” they are not really segmented and access controls alone are left to prevent successful attacks from occurring. But in the real world, hacking into a computer network is all about gaining a tiny foothold on the network, then leveraging that access to navigate around the network. The harder it is for these attackers to see the resources they want and navigate to them, the safer those resources are. In addition, the more protections that hackers need to circumvent during their attacks, the more likely they are to be detected. It should also be noted that network segmentation works just as well against the internal threat; it is just as difficult for an employee to gain access to a forbidden network segment as it is for an Internet-based attacker.

Increased security is not the only advantage of network segmentation. Instead of making network congestions worse, well implemented segmentation can actually reduce network congestion. This is because there are fewer hosts, thus less local traffic per segment. In addition, segmentation can help you contain network problems by limiting the effects of local failures that occur on other parts of the network.

The business reasons for implementing network segmentation are becoming more apparent every day. Increasingly, customers are demanding better information security from the businesses they employ. If the customer has a choice between two very similar companies, they will almost assuredly pick the company with better security. Simply being able to say to your customers that your network is fully segmented and controlled can improve your chances of success radically.