Control A.8.3Information access restriction
Access to information and other associated assets must be restricted in accordance with the established topic-specific policy on access control.
Where A.5.18 manages the rights a person holds, this is the restriction applied at the information itself — the enforcement point.
The principle is need-to-know: access to what the role requires, and not to what the system makes convenient. The failure is usually one of granularity. A system that can only grant access to everything or nothing forces a choice that defeats the policy, and the answer is either a different configuration or a compensating control, not a documented exception that never expires.
Dynamic access — where rights depend on context as well as role — is increasingly how this is implemented, and it does not change the requirement.
The place this control is most often quietly broken is reporting and analytics. Data copied into a warehouse or a spreadsheet for analysis leaves the system that enforced the restriction, and arrives somewhere that enforces something weaker.
How to put this in place
An access policy only protects information if the systems enforce it. Without that, permissions drift towards open, and confidential files end up visible to people who have no business reason to see them.
- Identify the systems and stores that hold your important information.
- Decide the access model, usually by role, with access closed by default.
- Configure permissions and sharing settings to match, removing open 'everyone' access and uncontrolled external links.
- Run a permission report on each key store and fix what is out of line.
- Reconcile permissions against joiner, mover and leaver lists, so access follows changes in role.
Evidence an auditor usually looks for: permission reports for key systems and shares, sharing settings, and records of permission reviews.
What is in the packs for this
From ISO 27001 Implementation & Certification Readiness. Each one helps with this requirement.
Annex A Control Implementation LibraryExcel
Its row in the Control Library: what it is for, practical steps, what an auditor samples, the usual owner, common mistakes and whether it usually applies.
Statement of Applicability TemplateExcel
Has its own row on the Statement of Applicability sheet, where you record whether it applies, why and how far it is implemented.