Zero Trust Controls That Work for Your Business

A compromised Microsoft 365 account can look exactly like a normal employee logging in. The attacker may have the right password, be using a familiar cloud service and know which invoices or customer records to search for. That is why zero trust controls matter. They reduce the assumption that a user, device or connection is safe simply because it is inside your network or has logged in once.

For Australian businesses, zero trust is not a single product to buy or a switch to turn on. It is a practical security approach: verify each request, give people only the access they need, and keep checking for signs that something has changed. Applied sensibly, it protects sensitive information without making everyday work unnecessarily difficult.

What are zero trust controls?

Traditional network security was often based on a perimeter. If someone was in the office, connected to the corporate network or signed in through a VPN, systems tended to trust them more freely. That model made more sense when applications, files and servers lived in one place.

Most businesses now use cloud software, remote access, mobile devices and third-party platforms. Staff may work from home, on site with a customer or between offices. Your accounting system, customer data and shared documents may all sit in different cloud services. A perimeter alone cannot provide enough protection.

Zero trust controls replace broad, ongoing trust with specific checks. Before allowing access, the system considers who is making the request, whether they have proved their identity, the condition of their device, the sensitivity of the information and the context of the request. It then allows, limits or blocks access accordingly.

The aim is not to treat employees as suspicious. It is to make a stolen password, infected laptop or unauthorised login much less useful to an attacker.

The controls that make the biggest difference

The best starting point depends on your systems, risks and current security maturity. For most small and mid-sized businesses, the following controls deliver meaningful improvement before more complex projects are needed.

Strong identity checks

Multi-factor authentication, or MFA, is one of the most effective zero trust measures. It requires a second proof of identity, such as an authenticator app prompt or security key, rather than relying on a password alone.

MFA should cover email, cloud storage, finance platforms, remote access and administrator accounts. However, not all MFA methods offer the same protection. App-based approvals and phishing-resistant security keys are generally stronger than SMS codes, which can be intercepted or redirected in some circumstances.

Conditional access adds useful context. For example, you can require extra verification when someone signs in from an unfamiliar country, prevent access from devices that do not meet your security standards, or block legacy login methods that do not support MFA. These settings need careful testing. A rule that is too strict can stop a legitimate employee from doing their job, especially when travelling or using specialised applications.

Least-privilege access

People should have access to the applications, folders and data required for their role, not every resource in the business. This is called least privilege.

A payroll officer may need access to employee records but not engineering documents. A contractor may need access to one project site for a fixed period, rather than your entire document library. Separating these permissions limits the damage if an account is compromised and reduces the chance of accidental changes.

Administrator access deserves particular attention. Staff who manage systems should use a standard account for routine work and a separate privileged account only when completing administrative tasks. Privileged access can also be approved for a limited time instead of being permanent. This adds a small amount of process, but it prevents one stolen account from becoming a pathway to every system.

Managed and secure devices

An approved user on an unmanaged or infected device can still create a serious risk. Device management allows you to check whether laptops and mobiles have current updates, disk encryption, screen locks and security software before they access business systems.

For a business using Microsoft 365, this might mean allowing access to confidential SharePoint files only from devices enrolled in management and meeting your compliance policies. Employees can still use their own devices for basic tasks where appropriate, but sensitive information receives a higher level of protection.

This does not always mean replacing every computer. Often, the work involves documenting your current devices, applying a consistent configuration, removing unsupported operating systems and setting a clear process for new starters and departing staff.

Segmentation and application controls

Not every system needs to communicate with every other system. Network segmentation separates areas of your environment so that a problem in one area does not spread freely. For instance, guest Wi-Fi should not provide a route to internal servers, and a warehouse device should not automatically access finance systems.

The same principle applies to cloud applications. Restricting access by role, location or device can reduce exposure. Application controls can also prevent sensitive files from being downloaded to personal storage, copied into unapproved apps or shared outside the organisation without review.

The right level of restriction depends on how your teams work. A field-based workforce may need more flexible mobile access than a back-office team. The answer is not blanket blocking. It is understanding which information is sensitive and providing safe ways to work with it.

Monitoring and response

Zero trust is not complete once access rules are configured. Accounts change, devices are replaced, staff move roles and attackers change their methods. Logging, endpoint protection and security monitoring help identify unusual activity, such as impossible travel logins, a sudden mass download of files or repeated failed access attempts.

A response plan matters just as much. Your team should know who can disable an account, isolate a device, contact affected customers and work with insurers or advisers if needed. Regularly testing these steps turns a written policy into something people can use under pressure.

Zero trust and AI use in the workplace

AI tools make access controls more relevant, not less. A staff member may be able to summarise documents, search internal knowledge or draft customer responses more quickly with an AI assistant. But the assistant must only retrieve information that person is authorised to see.

Before introducing Microsoft Copilot, a private AI assistant or a chatbot connected to internal documents, review existing permissions. If your shared drives are open to everyone, an AI search tool can make years of poorly organised content much easier to find. That may expose confidential HR records, commercial agreements or old customer information to the wrong people.

Good zero trust controls help you use AI safely. They establish clear identity checks, role-based permissions, device standards and audit records. They also support human review where it matters. An AI tool can triage incoming emails or extract details from invoices, while people remain responsible for approving payments, responding to sensitive customers and checking exceptions.

A sensible way to implement zero trust

Trying to change every access rule at once can frustrate staff and create avoidable downtime. We normally recommend beginning with a clear picture of your users, devices, applications and sensitive data. This identifies obvious gaps, such as former staff accounts, shared passwords, unsupported devices or broad administrator permissions.

From there, prioritise the controls that reduce the most risk with the least disruption. MFA, secure administrator access, device management and removal of unnecessary permissions are often sensible early steps. Pilot new conditional access rules with a small group before rolling them out more widely, and make sure employees understand what will change and where to get help.

Zero trust also needs ownership. Someone must review access when roles change, approve exceptions, follow up security alerts and assess new software before it is connected to company data. An internal IT team may manage this work, or a managed IT partner can provide the monitoring, policy support and hands-on administration needed to keep it moving.

Measure security without measuring inconvenience

Security controls should be tested against business outcomes, not just technical checklists. Useful measures include MFA coverage, the number of unmanaged devices, inactive accounts removed, privileged accounts reviewed and how quickly suspicious activity is investigated.

Also listen to the people using the systems. If staff are repeatedly blocked from legitimate work, they may find workarounds that create a bigger risk. A secure process that is practical enough to follow is far more valuable than an impressive policy nobody can use.

Zero trust controls work best as a steady improvement program rather than a one-off security project. Start with the access and data that would hurt most if compromised, improve the foundations, then build from there. Your people should be able to work with confidence, while your business has fewer opportunities for a single mistake or stolen password to become a major incident.