Building internal firewalls to curb insider attacks

4 March, 2017
Building internal firewalls to curb insider attacks

Internal firewalling can restrict malware flow between different segments of the organisation. (Image Shutterstock)

Traditionally cyberattacks on corporate networks have come from outside the organisation. With the growing usage of personal mobile devices and the rise of the Internet of Things, the danger now comes from within. The world moves swiftly, the IT security world even more so.

Just a couple of years ago, securing the enterprise would basically consist of protecting an organisation from external intruders. Today, the battle has changed ground. Education efforts from industry players have created higher levels of IT security awareness in the business world, and more firms have implemented basic security measures that can thwart direct attacks effectively.

This development is forcing hackers to go up the game by figuring out alternative ways to get their hands on valuable enterprise assets. One new strategy that is becoming more common across the world is for hackers to gain entry to a corporate network by targeting its weakest points.

Such points can include an unsecured employee mobile phone, or a workstation with limited access to corporate data. These weak points typically reside in low value segments of the corporate network. Once the hacker breaks in and gets a toehold, however, they can navigate to other more valuable parts of the network, which tend to be more rigorously protected from external attackers, quite easily.

This lateral movement modus operandi proves to be effective most of the time because many organisations do not isolate different segments of the network from one another. Moving from segment to segment is usually a breeze once hackers get into the network.

A few trends will make such attacks from within the organisation more common in the coming years:

#1 Adoption of employee-owned mobile devices in enterprises

These are often poorly secured and provide a weak point of entry into the organisation for hackers.

#2 Exponential growth of IoT devices

Early and even current versions of these devices are not designed with security in mind, and are tedious if not impossible to secure properly.

#3 Advances in hacking techniques

Traditionally, organisations deploy firewalls at the perimeter of the network for protection. Edge firewalls label all external traffic including Internet traffic as untrusted, while designating all intra-network traffic as trusted, and handle them in two distinct ways. There are no grey areas, no ambiguity.

Unfortunately the world is not black and white anymore.


Key takeaways

  • An internal segmentation firewall does not replace the edge firewall.
  • An internal segmentation firewall provides multiple touch points within a network in order to provide security between existing network boundaries
  • Internal firewalling can restrict malware flow between different segments of the organisation
  • Lateral movement modus operandi proves to be effective most of the time because organisations do not isolate segments of the network from one another
  • Moving from segment to segment is usually a breeze once hackers get into the network
  • With rise of attacks originating from weak segments of the network the line delineating trusted and untrusted traffic has blurred

With the rise of attacks originating from weak segments of the network, the line delineating trusted and untrusted traffic has blurred. Merely deploying firewalls at the edge of the network is no longer adequate – organisations need to re-architecture their network such that internal firewalling can restrict malware flow between different segments of the organisation.

According to research firm Forrester, enterprises have built strong perimeters. Today well-organised cybercriminals have recruited insiders and developed new attack methods that bypass current security protections. Security and risk professionals must now make security ubiquitous throughout the network, not just at the perimeter.

Forrester advocates the zero-trust security model, where the network is securely segmented, and all traffic is inspected and logged. With such a model, the information flow between an engineer and a marketing colleague seated next to each other, will no longer proceed unchecked.

Since these two employees are assigned different network segments and an internal segmentation firewall is in place, proper policies will be applied and logs will be generated for any traffic traversing between the two departments.

Internal segmentation firewall comprises two kinds of technologies:

#1 Policy-based segmentation that identifies a user’s parameters, and dynamically and consistently enforces a security policy controlling the user’s access to enterprises resources

#2 Firewall segmentation that divides up the internal network to enable traffic analysis, logging and full security control

An internal segmentation firewall does not replace the edge firewall. Instead, an internal segmentation firewall provides multiple touch points within a network in order to provide security between existing network boundaries. Or it can create entirely new segments inside of existing network boundaries. It also improves visibility by letting IT management see all layers of the network in one pane of glass.

Depending on the level of security needed between each network segment, the types of protection enabled will vary. Once a firewall is deployed into each segment of an enterprise network, its policy, logging and various modern detection features can help identify and quarantine users that have been compromised.

Also, firewalls would make it much harder for hackers to do reconnaissance and discovery even if they have started to make their way inside the company network.

Internal segmentation firewalls should work in synchronisation with one another, leveraging threat intelligence and being complemented by advanced persistent threat detection solutions. These include sandboxing and endpoint security solutions, so that actions can be taken to identify compromises and quarantine them as soon as they are discovered.

Traditional enterprise objections to putting a firewall in front of each network segment have been around performance and price. Because intra-network traffic volume can be many times that of Internet traffic volume, not many firewalls have the capability to handle the workloads without significant latency. Those that can handle it, when deployed in large numbers to cover each network segment within the enterprise, can make the cost prohibitive for many organisations.

Today however attainable solutions exist. Modern firewalls that leverage custom ASIC chips can be fast enough to handle internal firewalling and be cost effective at the same time.

Some may recall that per-port security was all the rage a few years ago, until implementation hurdles put an end to that promise. Current internal segmentation firewall technology is a step towards reviving that promise. As technologies in switching and access port security evolves and performance improves, we will be able to combine them with internal segmentation firewall to reach that goal.

The concept of internal segmentation firewalling has put the network security industry on the cusp of an exciting era. Firms that want to take their operations and their business, one step ahead of the competition should take advantage of it.


Michael Xie is Founder, President and Chief Technology Officer at Fortinet.

With rise of attacks from within weak segments of the network, the line between trusted and untrusted traffic has blurred, says Michael Xie from Fortinet.


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