The three principles of zero trust are: verify explicitly, use least privilege access, and assume breach. This will change the security approach from “trust by default” to “trust only after verification”.
In this article, let’s explore the concepts of zero trust and how to apply them to cybersecurity, compliance, and IT planning. Each principle is explained with examples to help you understand the concept and its impact.
What Does Zero Trust Mean in Cybersecurity?
Zero trust is a security model that has no default trust for users, devices, or network connections. Access is granted only after reviewing the identity and credentials, including the trust state of the device, context, and permissions.
This principle is important, as today’s advanced attacks are designed to use trusted methods. Therefore, implementing poor access controls based on trust may allow attackers to gain control over your account, data or system.
What Are the Three Core Principles of Zero Trust?
1. Verify Explicitly: Validate Every Access Request
‘Verify explicitly’ means you should check every access request using as much relevant information as possible.
That usually includes the following:
- Who the user is
- Whether the device is secure
- Where the request is coming from
- What resource is being requested
- Whether the request looks unusual
In simple terms, don’t assume someone should have access just because they are inside the network or already signed in.
How Does Explicit Verification Work in Practice?
For example, on the login page of the company’s website, the system shows a password prompt when an employee attempts to access the login. The system could validate access to the company dashboard with Multi-factor Authentication, device health, location, risk signalling, etc.
Why Is Explicit Verification Important?
Why it matters: Passwords alone are easy to steal. Explicit verification makes it harder for an attacker to use a stolen login and harder for a risky device to slip through.
2. Use Least Privilege Access: Grant Only Necessary Permissions
Least privilege means providing users, applications, and devices with just the access they need to do their work and nothing more.
People who only require read access to a file should not have admin or editorial rights. If an application only requires one database, then it should not be allowed to access the whole network.
What Is an Example of Least Privilege Access?
Example: A support agent might need access to customer tickets, but he cannot access the payroll records. A zero-trust configuration will provide each user access only to the information they need.
Why Does Least Privilege Matter for Zero Trust Security?
Why it matters: When an account is breached, least privilege prevents editing or deleting the important documents or files and reduces the impact. Using the least privilege helps businesses and limits attackers from causing more damage.
3. Assume Breach: Design Security for Potential Compromise
Assume a breach means that the security is designed as if some malicious attacker is already present within your environment.
It‘s not that you expect to fail every time. It’s about designing a system that contains the damage, quickly recognises abnormal activity, and prevents the attacker from corrupting files or exposing information.
That includes:
- Segmentation of networks: Dividing large networks into smaller manageable sections will allow attackers easier access to all resources. So break large networks into smaller configurations or sections.
- Detecting odd behaviour: Look for odd behaviour of a system user or resource, which might be a symptom of an attack.
- Logging of access events: Logs related to systems and applications should be maintained for all unauthorised accesses to files or systems.
- Re-activation of trust: Being personally re-evaluated is continuous re-evaluation (verification) of trust, including user, devices, services, etc.
- Limited to sensitive systems: Access to confidential files is allowed only for authorised personnel.
What Does “Assume Breach” Look Like in Practice?
Example: If an employee account is hijacked, zero trust assumes the attacker may try to move from email to file storage to internal tools. Security controls should slow that movement and raise alerts.
Why Is Assuming a Breach Important?
Why it matters: Many breaches are discovered late. Assuming a breach helps organisations contain incidents more quickly and reduce their impact.
How Do the Three Zero Trust Principles Work Together?
These principles are most effective when used together:
- ‘Verify’ explicitly checks every request.
- Least privilege limits what a successful user or attacker can do.
- Assume breach prepares the environment for compromise and rapid containment.
If you only do one of these, the model is incomplete. For example, strong login checks help, but if users still have too much access, a compromised account can do serious damage. Likewise, limited access helps, but if you never verify requests properly, attackers may still get in.
What Are the Most Common Mistakes When Adopting Zero Trust?
- Treating Zero Trust Like a Single Product: Zero trust is a strategy, not a checkbox. Buying one tool does not make an environment zero trust.
- Trusting the Internal Network Too Much: Older models often trusted anything inside the perimeter. Zero trust removes that assumption.
- Giving Broad Access “for Convenience”: Too much access often survives because it is easier for IT to manage. But convenience can increase risk.
- Failing to Review Access Over Time: People change roles, projects end, and devices age. Access should be reviewed regularly.
When Is a Zero Trust Security Model Most Useful?
Zero trust is especially valuable for organisations that use the following:
- Organisations that use cloud apps
- Support remote or hybrid work
- Store sensitive customer or financial data
- Have many internal tools and privileged users be aligned with
- Need stronger protection against phishing and account takeover
It can also help smaller organisations, but the rollout should align with the company’s size, risk level, and budget.
Frequently Asked Questions About Zero Trust
1. Is Zero Trust the Same as Zero Permissions?
No. Zero trust does not mean nobody gets access. It means access is carefully checked and limited.
2. Does Zero Trust Replace Firewalls?
No. Firewalls can still be useful. Zero trust adds a another layer of security that focuses on identity, device posture, and access control.
3. Is Multi-Factor Authentication Part of Zero Trust?
Yes, often. MFA supports explicit verification, but it is only one part of the model.
Also Read: What Are the Benefits and Challenges of Zero Trust?
