How to Implement ISO 27001 Annex A 8.3 Information Access Restriction

Implementing ISO 27001 Annex A 8.3 requires the technical enforcement of Information Access Restriction protocols to limit data availability based on verifiable identity and context. This control mandates granular file system permissions, database schema limitations, and conditional access rules to prevent unauthorized discovery and ensure data confidentiality across the infrastructure.

ISO 27001 Annex A Information Access Restriction Implementation Checklist

Use this implementation checklist to achieve compliance with ISO 27001 Annex A 8.3. This control demands rigorous, technical enforcement of access rights at the data layer, moving beyond simple policy declarations to actual granular restrictions within your file systems, databases, and application code.

1. Configure Granular NTFS/NFS Permissions

Control Requirement: Access to information must be restricted in accordance with the established access control policy. Required Implementation Step: access your file servers or cloud storage repositories (e.g., SharePoint/S3). Remove the “Everyone” or “Domain Users” groups from the root folders of sensitive directories. Explicitly assign Read/Write permissions only to specific Security Groups (e.g., “SG-Finance-RW”) rather than individual users.

Minimum Requirement: Default permission inheritance is broken for sensitive directories; no “Open Access” folders exist.

2. Implement Database Schema-Level Restrictions

Control Requirement: Access restrictions must extend to data stored within application databases. Required Implementation Step: Open your database management console (SQL Server Management Studio, pgAdmin). Create specific database roles with the absolute minimum privileges required (e.g., `db_datareader` only). Ensure the application service account does not run as `sa` or `root`, preventing a SQL injection vulnerability from accessing the entire data warehouse.

Minimum Requirement: Applications connect to databases using restricted service accounts, not administrative credentials.

3. Enforce Conditional Access Policies

Control Requirement: Access must be restricted based on the context of the connection. Required Implementation Step: Configure your Identity Provider (Azure AD/Okta) to enforce “Conditional Access”. Block authentication attempts to sensitive information assets if the request originates from a non-compliant device, an unknown IP address, or a country outside your operating region.

Minimum Requirement: Valid credentials fail to grant access if the device is unmanaged or the location is suspicious.

4. Restrict Internal Search Indexing

Control Requirement: Information should not be discoverable by unauthorised personnel. Required Implementation Step: Configure your internal search tools (e.g., SharePoint Search, ElasticSearch, Windows Indexing). Exclude sensitive paths (like HR/Payroll folders) from the global search crawl. Test this by logging in as a junior employee and searching for “Salary” or “Redundancy”.

Minimum Requirement: Sensitive document titles do not appear in global search results for standard users.

5. Hardcode API Scope Restrictions

Control Requirement: Programmatic access to information must be limited to specific functions. Required Implementation Step: Review your API Gateway or OAuth configuration. Ensure that API tokens issued to third parties or internal microservices have limited “Scopes” (e.g., `read:user_profile` only), rather than full wildcard access (`*`).

Minimum Requirement: API keys effectively restrict actions; a “Read” token cannot perform a “Delete” operation.

6. Deploy Just-In-Time (JIT) Access Elevation

Control Requirement: Privileged access to information should be temporary. Required Implementation Step: Implement Privileged Identity Management (PIM) or `sudo` restrictions. configure systems so that administrators have zero standing access to sensitive data. They must request access for a specific time window (e.g., 2 hours) to perform maintenance, after which permissions are automatically revoked.

Minimum Requirement: No accounts possess permanent, 24/7 standing administrator access to live data.

7. Segregate Multi-Tenant Data Logic

Control Requirement: Information belonging to different clients or entities must be isolated. Required Implementation Step: If running a SaaS or multi-client platform, audit the code logic. Ensure that every database query includes a `WHERE TenantID = X` clause. Ideally, implement Row-Level Security (RLS) at the database engine level to act as a fail-safe against code errors.

Minimum Requirement: A code bug in the application layer cannot cause one client’s data to leak to another.

8. Mask Sensitive Data in Non-Production Environments

Control Requirement: Production information must not be accessible in test environments. Required Implementation Step: implement an ETL (Extract, Transform, Load) pipeline that anonymises or pseudonymises data when moving it from Production to Staging/Dev. Replace real names and credit card numbers with format-preserving dummy data.

Minimum Requirement: Developers working on the ‘Test’ environment cannot see real customer PII.

9. Prevent Local Drive Mapping for Remote Users

Control Requirement: Information must be prevented from flowing to uncontrolled storage. Required Implementation Step: Configure Group Policy Objects (GPO) or VDI (Virtual Desktop Infrastructure) policies to disable “Drive Redirection” and “Clipboard Sharing”. This prevents remote users from copying files from the secure server environment to their local, unmanaged home PC desktop.

Minimum Requirement: Data cannot be copied/pasted or saved from the secure corporate network to a personal device.

10. Execute Negative Access Testing

Control Requirement: Restrictions must be verified to ensure they work as intended. Required Implementation Step: Conduct a manual internal audit where you explicitly attempt to access files, databases, or network segments you should not have access to. Document the “Access Denied” screens as positive evidence of effective control implementation.

Minimum Requirement: Documented evidence of failed access attempts by unauthorised accounts.

ISO 27001 Annex A 8.3 SaaS / GRC Platform Implementation Failure Checklist

Comparison of SaaS Compliance Claims vs. Real-World Access Restriction

Control Requirement	The ‘Checkbox Compliance’ Trap	The Reality Check
Directory Permissions	GRC tool asks: “Are permissions defined?” (Yes/No).	Fails if the “Everyone” group still has Read access to the CEO’s folder. Only a script scanning ACLs reveals this.
Database Security	SaaS platform checks if “Encryption is On”.	Fails if the web app connects as `sa` (System Admin), meaning a hacker can drop the entire table via SQL injection.
Search Visibility	Not checked by automated scanners.	Fails if a junior intern can search “Bonus Scheme” and see the filenames of executive compensation plans.
Test Data	Policy document says “We don’t use live data in test.”	Fails if a developer simply restored a Prod backup to Dev to “debug an issue” quickly. Technical masking is required.
Temporal Access	Tool checks if you have an Admin list.	Fails if those admins have had full access 24/7 for 5 years. True security requires JIT (Just-In-Time) access logs.
Clipboard/Drive Blocking	Questionnaire: “Do you secure remote access?”	Fails if a user can `Ctrl+C` a client list from Citrix and `Ctrl+V` it into their personal Gmail.
Verification	Green tick for “Policy Uploaded”.	Fails if you haven’t actually tried to break in. Compliance is proven by the “Access Denied” message, not the policy PDF.

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