What is Group Policy?
Group Policy is a feature within Active Directory that allows administrators to centrally manage and enforce settings and security rules on Windows systems within a domain.
In OT environments, Group Policy is often used to apply standard configurations, security settings and access restrictions to engineering stations, HMIs and servers.
🧠 How does Group Policy work?
- Administrators create Group Policy Objects (GPOs) in the Active Directory environment
- GPOs are linked to an OU (Organizational Unit) within the AD hierarchy
- When a Windows device or user signs in, the relevant GPOs are applied
- Settings are automatically enforced via the Group Policy Client
- Examples of settings:
- Password policies
- Disk encryption
- USB port restrictions
- Disabling Windows Update
- Applying scripts or firewall rules
Group Policy uses LDAP and Kerberos for distribution and authentication.
🏭 Application of Group Policy in OT networks
- Securing Engineering Stations with fixed settings and encryption
- Preventing user changes on HMIs and workstations
- Automatically adding log servers (Syslog, SIEM) or firewall rules
- Standardising local Firewall settings on machines in zone 2–3
- Managing user permissions with RBAC
With GPOs, you keep Windows systems in industrial environments uniform, controllable and secure.
🔍 Group Policy vs. MDM (Modern Device Management)
| Aspect | Group Policy (GPO) | MDM (e.g. Intune) |
|---|---|---|
| Management location | On-premises via Active Directory | Cloud-based via Entra ID |
| Operating system | Windows (most appropriate) | Windows, Android, iOS, macOS |
| Application | Rule-driven domain environment | Mobile and hybrid devices |
| Use in OT | Yes, widely used standard | Limited – often only for remote management |
🔐 Security aspects
- Use GPOs to automate security hardening (e.g. disabling RDP, PowerShell)
- Prevent users from modifying settings (via UAC and Registry Policies)
- Restrict permissions with User Rights Assignment and RBAC
- Audit policy application via
gpresultor event logging - Combine with SIEM for detection of deviations or policy changes
Well-managed GPOs help with compliance to standards such as IEC 62443, ISO 27001 or NIS2.
📌 In summary
Group Policy is a powerful mechanism for centrally managing Windows settings, essential in industrial environments for standardisation, security and manageability. By configuring GPOs correctly, you increase the resilience of OT systems against errors and attacks.