Rather than relying solely on perimeter defences, organisations now need to find other ways to protect users and assets regardless of their location. Those assets could be on-premise, on a cloud platform, or at a user’s home.
One approach gaining increasing attention is zero trust. It’s a strategy that is built on a range of underlying security principles including defence in depth, the separation of authentication and authorisation, least privilege, and network segmentation.
What zero trust is not is a security silver bullet. There are numerous tools on the market that claim to deliver it but, in reality, the strategy requires a number of steps and a variety of different components.
Some clear guidance on what is required has been provided by both the US-based National Institute of Standards and Technology (NIST) and the Australian Cyber Security Centre (ACSC). According to NIST, the key requirements for zero trust are:
1. Treat all data and systems as resources:
Controls must be applied to anything within an IT infrastructure that is a resource. This includes everything from a Word file on a server through to a complex application running on a cloud platform.
2. Secure all communication:
All data traffic between devices, applications, and databases needs to be secured. Encryption is an effective way to achieve this, and it should also be extended to protecting data at rest. This approach can also provide solid protection against ransomware attacks.
3. Grant access to resources on a per-session basis:
Security can be further enhanced if there is no persistence of access. In practice, this means that users and applications need to be authorised each and every time they seek access to a resource. Just because someone has logged on once, this should not mean they have ongoing access.
4. Implement dynamic authorisation:
In a zero-trust environment it’s important to rely on more factors than simply log-in credentials. Other variables should be added to the mix including geographic location, the device being used, and the historical activity of the party requesting access. Part of this process will involve examining behavioural characteristics to determine that a user or resource is actually who or what they claim to be.
5. Monitor and measure the posture of assets:
Resources and activity on a network should be monitored to determine what constitutes normal operating conditions. Once this has been confirmed, security teams can then respond when activities occur that fall outside those parameters which could be security incident indicators.
6. Make authentication and authorisation dynamic:
It’s important to avoid keeping authentication and authorisation in place for extended periods. Users and applications should be required to constantly prove their identity before being granted access to the resources or services they are requesting.
7. Collect as much information as possible on current assets:
A lot of information can be collected from enterprise IT systems, but unfortunately much of it is not acted upon. An example could be workflows that are bypassing security policies or intent. Such activity should be flagged for closer inspection to determine whether it is authorised or being conducted by a malicious party.
Rather than being achieved through the deployment of a single software tool or process, true zero trust requires the introduction of a portfolio of components and activities to be truly effective. It’s important to understand exactly what exists within your infrastructure, what risks are being faced, and exactly what needs to be done to overcome them.
Thankfully, most organisations will already have in place many of the resources required to achieve a zero trust strategy and so won’t need to start from scratch. It’s a matter of building on existing security measures and extending them to cover all resources within their information environment – be that on-premise, cloud or a combination.
Flexible and hybrid work practices are likely to remain a feature of life in coming years. Taking the steps necessary to achieve true zero trust will be well worth the effort.