Definition
Zero Trust is a security framework that requires all users, devices, and applications to be verified, authenticated, and continuously validated before being granted access to resources, regardless of whether they are inside or outside the network perimeter.
People Also Ask
Common questions about Zero Trust answered by our security experts.
Zero Trust in Practice
Zero trust is a design principle, not a product. It holds that no request should be trusted because of where it came from — every access decision is made on identity, device state and context, and verified continuously rather than once at a boundary.
The phrase is heavily marketed, which obscures how practical the underlying idea is. It is a response to a specific observed failure: attackers who get inside a network move freely, because internal position was treated as authorisation.
What it actually requires
Identity as the primary control, with strong authentication and access decided per request rather than per session. Device health as an input, so an unmanaged or non-compliant machine is treated differently. Least privilege, so authorisation grants the minimum needed. Segmentation, so reaching one system does not imply reaching others. And comprehensive logging, since continuous verification requires continuous visibility.
None of that is novel individually. What zero trust contributes is the discipline of applying it consistently rather than only at the perimeter.
Where implementations go wrong
Buying a product labelled zero trust and considering the work done. Applying the model to remote users while leaving the internal network flat and implicitly trusted. Excluding service accounts and legacy systems — which is where attackers concentrate precisely because everyone excludes them. And attempting a complete transformation rather than sequencing it.
The sequencing that works starts with identity: strong authentication everywhere, legacy protocols disabled, conditional access enforced. Then the highest-value applications move to per-application access. Then segmentation reduces what reaching any one system is worth.
Measuring progress without a product to point at
Because it is a principle rather than a purchase, zero trust programmes struggle to demonstrate progress. The measures that actually describe it are unglamorous and concrete.
What proportion of applications require strong authentication? How many identities are excluded from conditional access, and is that number falling? What can a standard workstation reach that it does not need? How many applications are published per-application rather than by network access? How long does a session remain valid after a risk signal changes?
Those five numbers describe the architecture more honestly than any maturity model, and each of them moves as a result of work somebody did rather than a product somebody bought.
It is also worth being clear about what the model does not change. An attacker with valid credentials on a compliant device is authorised by design, which is why strong authentication, session monitoring and behavioural detection remain necessary alongside it. Zero trust removes implicit network trust; it does not remove the consequences of credential compromise.
A common mistake worth avoiding
Where to start
Disable legacy authentication protocols and list every identity currently excluded from conditional access. That is the first genuine step, it requires no new product, and it closes the bypass attackers use most.
See zero trust architecture. GuardsArm delivers zero trust security.
Related Terms
Access Control
Access control is a security mechanism that regulates who or what can view, use, or interact with resources in a computing environment. It enforces policies that grant or deny permissions based on user identity, role, or other attributes.
Multi-Factor Authentication
Multi-Factor Authentication (MFA) is a security method that requires users to provide two or more verification factors to gain access to a resource. It combines something you know (password), something you have (token), and something you are (biometrics).
Network Security
Network security encompasses the policies, practices, and technologies designed to protect the integrity, confidentiality, and accessibility of computer networks and data. It includes both hardware and software solutions that defend against unauthorized access and cyber threats.
Authentication
Authentication is the process of verifying the identity of a user, device, or system before granting access to resources. It typically involves credentials such as passwords, biometrics, security tokens, or digital certificates.
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