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Calculating clear-cut network segmentation ROI can be tricky. It is a preventive investment, a vaccination against cyberattacks. Thinking it is unnecessary? Or waiting until it is too late?

Why is network segmentation required?

Many businesses have an IT architecture based on systems designed during a politically stable era. Frequently the architecture has grown over the years while getting current information on e.g. electricity consumption, ordering 24/7 services or teleworking has become standard. The result is that SCADA systems, business systems and the web are interconnected. Therefore, it is difficult to know how many paths lead to critical information. Only when dedicated tests are carried out through a risk and safety analysis all loopholes can be detected.

However, it is neither practical nor economically justifiable to protect all information in the same way. To safeguard critical information, strict network segmentation must be applied, combining physical separation with logical separation.

Where is physical separation vital?

Critical information requires physical separation. Simply put, an isolated island is created without connection to the outside world. This minimizes the risk area – the attacker has to sit at the computer containing the critical information.

Physical separation is very effective, but to work today a controlled exchange of information has to be possible without compromising isolation. This requires certified solutions that meet military standards, thus guaranteeing function and safety.

physical separation

Where is logical separation appropriate?

Everywhere besides protecting critical information. Office networks should use logical separation. Different parts of the business create their own zones – finance, marketing, sales, customer service, etc. – each with different authority. As a co-worker, you access only what you need to do your job, i.e. relevant documents, not the entire folder structure.

Logical separation works as fortress’ ring-walls making it difficult for attackers to penetrate the mass of the system and infiltrate the entire IT architecture. Security is achieved with products that reduce the risk area, thus limiting cyber attack damages.

logical separation

Are firewalls enough?

Today’s firewalls cannot separate administration with data flow, making them susceptible to attacks. And few firewalls offer high assurance. Entire batches could be manipulated, and when installed they expose attack points.

Additionally, when firewalls are managed through cloud services, outsourcing further increases risk exposure.

Firewalls should be used for their intended purpose: as excellent exterior protection. For logical separation, different firewalls should be used, supplemented by a protocol that requires several people to approve changes and understand the consequences of switching firewalls on or off.

When can firewalls be managed through cloud services?

For office networks with limited access to critical information, cloud services are a cost-effective and good solution.

Important advice

Involve management to identify critical information and the real threats to it. Apply a combination of logical and physical separation – from a safety point of view, this is always recommended.


The world is changing. Established truths just a few years ago are no longer relevant. The means to carry out cyber attacks that used to be reserved for a few, or were mere academic ideas, are accessible to more and less competent attackers. At the same time political development has dramatically increased exposure. An increasing number of businesses therefore need the kind of effective protection previously only used by defense forces and intelligence agencies. Threats that recently were unlikely are likely now.

Vulnerabilities in standard products

Fact: vulnerabilities are implanted in standard products. These vulnerabilities can be exploited for criminal and military purposes. Statistics on detected malicious code show they currently exceed 700 million versions ( Beyond the statistics, unexplored threats are just waiting to be used.

Taking this into account, continuing the prevailing patch and update strategy will not lead to any improvement as it is unlikely that all holes can be patched this way. By definition, only detected holes can be patched – undetected ones remain as latent threats regardless how rigid the patch and update strategy.


Logical or physical separation?

By utilising logical separation with for instance VLAN, and otherwise sharing hardware for storage, networking and firewalls, logical separation is achieved. This is positive – but can lead to a false sense of security.

Systems solely based on this kind of logical separation pose a high risk. Just one small mistake, intentional or accidental, in one of the components gives the attacker the go ahead to create havoc inside the system. In a world where vulnerabilities are actively implanted in many systems, this design philosophy offers too large a risk.

A major difference between logical and physical separation is that the latter also provides protection against undetected vulnerabilities. And in an environment where undetected threats are highly likely, it is necessary to use physical separation as part of the protection.

Combining logical and physical separation

By subdividing systems into zones, VLAN can be used in the zones and physical separation can be used at zone borders. This way, the attacker has to break through zone border protection – instead of simply entering the back door. Furthermore, risks are significantly reduced when zone border protection is based on white listing information – i.e. import and export of data is controlled and without packaging (= without transport protocols).

Security is always a balance between function and safety. It is easy to build safe systems without function – and vice versa. The real art is creating systems that deliver both.