NIST 800-171 Control 3.5.1: User Identification
User identification is the foundation of system accountability and access control under NIST 800-171. This control requires you to uniquely identify all users, processes acting on their behalf, and devices accessing your systems. Without proper identification, you cannot enforce access policies, audit user actions, or detect unauthorized activity.
What this means
Control 3.5.1 mandates that your organization establish and maintain mechanisms to uniquely identify system users, processes executing on behalf of users, and devices connecting to your systems. This means assigning unique identifiers (usernames, service accounts, device IDs) to every entity accessing protected information, enabling you to track who did what, when, and from where. Proper identification supports both real-time access control and forensic audit trails required by NIST 800-171.
How to comply
- 1.Establish a unique identifier scheme for all system users (usernames, employee IDs, or similar)
- 2.Create and maintain an authoritative registry or directory (such as Active Directory) of all users and their identifiers
- 3.Implement service accounts with unique identifiers for processes that act on behalf of users
- 4.Assign unique device identifiers to all hardware accessing your systems (laptops, servers, mobile devices, IoT devices)
- 5.Enforce identifier usage through login credentials, multi-factor authentication, or certificate-based mechanisms
- 6.Log all user, process, and device identifiers with every access event for audit purposes
- 7.Review and update identifier assignments when users change roles or leave the organization
- 8.Document your identification policies and maintain records of identifier assignments
Evidence auditors look for
- Active Directory or LDAP configuration showing unique user identifiers and group memberships
- Service account inventory with documented purposes and unique names
- Device management records (MDM/MMS) listing all enrolled devices with assigned identifiers
- System access logs showing user, process, and device identifiers for each authentication event
- User provisioning and deprovisioning procedures with supporting tickets and completion records
- Network device configurations showing device identification requirements (MAC addresses, certificates)
- User identification policy document with assignment and maintenance procedures
- Off-boarding checklist confirming removal of user and device identifiers from systems
Frequently asked questions
When will FAQs be available?
The FAQ for this control is currently being prepared.
GRCWatch automates user and device identification tracking by integrating with your directory services and access logs, giving you a real-time inventory of all identifiers and continuous evidence collection for 3.5.1 compliance without manual audits.
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