What is IAM?

Most security decisions come down to two questions: who are you, and what are you allowed to do? Identity and Access Management (IAM) is the field that deals with both. Authentication checks who you are, usually with a password plus a second factor. Authorization decides what you can do once you are in. In a company with thousands of employees and hundreds of applications, it gets messy quickly.

Some terms appear all the time. SSO (single sign-on) lets people log in once and use several systems. MFA (multi-factor authentication) asks for a second proof, such as a code, a fingerprint or a push notification. RBAC (role-based access control) links permissions to a job role, so nobody has to assign them person by person.

Why the old model stopped working

For a long time, network security worked like a castle. A company built a strong wall around its network, and everyone behind the firewall was trusted automatically. Remote workers got in through a VPN.

That only made sense while there was a clear line between inside and outside. Today people work from home, airports and cafés abroad. Applications run in the cloud, and vendors and partners need access too. Over the years the wall got so many doors that it protected very little.

Stolen credentials made things worse. With a single valid login, an attacker could move around freely, because everything inside was trusted by default. Breach reports keep showing the same thing: stolen or abused credentials are behind roughly one in five incidents.

What Zero Trust actually means

Zero Trust turns the old idea around. Being inside the network does not earn any trust. Every request is checked first: who is asking, from which device, under what conditions, and for which resource. Access is granted only after that.

You can’t buy Zero Trust as a product, whatever some sales presentations suggest. It is an architecture and a way of thinking. Identity and context are checked all the time, not just at login.

How the technology works in practice

Today this idea is usually delivered through a cloud-based security service, often called Zero Trust Network Access (ZTNA) and part of a wider category known as Security Service Edge (SSE). Instead of connecting a laptop to the corporate network, the user’s device connects to a cloud service that sits in between.

This service checks the user’s identity, the health of the device and the company’s policies. If everything looks fine, it connects the user to one specific application, and nothing else. The user never sees the rest of the network, and the applications are not exposed to the internet, so attackers can’t scan them. Because all traffic passes through the service, it can also inspect it for malware and data leaks.

For the user, this feels like simply opening an app. For the company, every connection is limited and checked.

The main building blocks

Strong identity. Everything starts here. Use MFA for everyone wherever you can, not only for administrators. Studies suggest that MFA blocks the large majority of account takeover attempts, in some cases more than 99%. Phishing-resistant options like FIDO2 security keys and passkeys are better still.

Least privilege. People, and now also AI agents and service accounts, should get only the access they need for their work. Extra permissions shouldn’t stay around “just in case”. Review access regularly and remove it when it is no longer needed.

Micro-segmentation. Instead of one flat network, you split it into small, separate zones, or even give access application by application. If an attacker gets into one zone, they shouldn’t be able to walk straight into every other system.

Continuous monitoring. None of the above works without it. Device health, location and unusual behavior all help decide whether a request should be approved right now, not just whether the password was correct five minutes ago. A SIEM, for example, can raise an alert if the same account logs in from two countries within an hour.

Common mistakes

“Zero Trust” is a popular marketing term. Some vendors attach the label to a single product and sell it as the full solution, but one product is never enough. Another typical mistake is to roll out MFA and then stop, even though it is only the first step.

Legacy systems are a problem too. Many older applications check identity once, at login, and not on every request. Adding Zero Trust controls later is possible, but slow.

The classic failure looks like this: an old remote access account that nobody uses anymore, but nobody has disabled, and with no MFA. One leaked password is enough, and the attacker is inside.

How IT teams can get started

Begin with an inventory. It isn’t exciting work, but you can’t skip it: who has access to what, in every system, right now? Organizations are often surprised: they find old accounts nobody disabled, or permissions granted years ago for finished projects.

Next, add MFA to the most important systems first, such as finance, admin consoles and anything that holds sensitive data. Then extend it to everything else. After that, apply least privilege step by step. If you remove too much access at once, workflows break and employees start to resist the whole project.

Once that works, start replacing the VPN with a Zero Trust access service, one group of applications at a time. Separate the systems that would do the most damage if they were compromised, and plan monitoring from day one instead of adding it after an incident.

In the old model, being inside the network was enough to be trusted. Zero Trust changes this. Identity and context are checked on every request, access is kept to a minimum, and a successful login yesterday does not mean that the user can be trusted today. Building this properly takes time, but recovering from a breach usually takes a lot longer.

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