Understanding Authentication Policy Silos in Windows Server 2012 R2 (2023)

In the dynamic landscape of IT security, effective management of high-privilege credentials is paramount. Windows Server 2012 R2 introduces a powerful feature known as Authentication Policy Silos, offering administrators a robust toolset to contain and control access to critical systems. This article delves into the intricacies of Authentication Policy Silos, exploring their creation, application, and the heightened security they bring to Windows environments.

Authentication Policy Silos: A Strategic Approach

Authentication Policy Silos serve as containers within Active Directory Domain Services (ADDS), allowing administrators to meticulously assign user accounts, computer accounts, and service accounts. By organizing sets of accounts within these silos, administrators can streamline management and mitigate the risk of credential theft by restricting access to specific resources.

Creating Authentication Policy Silos

Creating an Authentication Policy Silo involves using either the Active Directory Administrative Center or the Active Directory Windows PowerShell cmdlets. These silos act as gatekeepers, hosting a curated collection of high-privilege users whose access is governed by authentication policies.

Authentication Policies: Fine-Tuning Access Control

Authentication policies, intricately linked to Authentication Policy Silos, define the parameters for Kerberos protocol ticket-granting ticket (TGT) lifetime properties and access control conditions for different account types. Let's explore how these policies function for various account types.

User Authentication Policy

User authentication policies, when applied to the Protected Users security group, ensure rejection of attempts to authenticate using NTLM. These policies enable administrators to configure TGT lifetimes and restrict the devices from which a user account can sign in.

Service Authentication Policy

Standalone managed service accounts, group managed service accounts, or custom account objects fall under the service category. Authentication policies for services enable precise control over device access conditions, safeguarding service account credentials.

Computer Authentication Policy

Computer accounts, fundamental to network infrastructure, benefit from authentication policies that set access control conditions based on user and device properties. These policies, while not configuring TGT lifetimes for computers, add an extra layer of security by rejecting NTLM authentication attempts.

Implementation: How It Works

Understanding the mechanics of Authentication Policy Silos and authentication policies is crucial for effective implementation. Let's delve into the intricacies of how these components collaborate, especially in conjunction with the Protected Users security group and the Kerberos protocol.

Kerberos Protocol Integration

Authentication Policy Silos and policies seamlessly integrate with the Kerberos protocol, bringing forth a secure authentication mechanism. The protocol's utilization ensures the exclusive use of advanced encryption types, adding a layer of defense against potential threats.

Restricting User Sign-In

Authentication policies, when applied to accounts, extend their influence to services using those accounts. This feature becomes invaluable when limiting the usage of a password for a service to specific hosts, enhancing overall security.

Restricting Service Ticket Issuance

Authentication policies play a pivotal role in determining whether a service ticket is issued or denied. By enforcing access control conditions, administrators gain granular control over which accounts can access specific services, fortifying the overall security posture.

Protected Users Security Group: Enhancing Security Measures

The integration of Authentication Policy Silos aligns seamlessly with the Protected Users security group, triggering non-configurable protections on Windows Server 2012 R2 and Windows 8.1 devices. This elevated security stance includes restrictions on authentication methods, encryption types, and delegation capabilities.

Troubleshooting and Event Logging

A comprehensive approach to Authentication Policy Silos necessitates effective troubleshooting. Understanding the associated event messages, recorded in the Applications and Services Logs, empowers administrators to identify and address potential issues promptly.

Event ID 101: NTLM Sign-In Failure

This event signifies an NTLM authentication failure due to configured access control restrictions, emphasizing the importance of aligning authentication policies with organizational security requirements.

Event ID 105: Kerberos Restriction Failure

Kerberos restriction failures, documented under Event ID 105, highlight instances where a TGT is denied because the device fails to meet enforced access control conditions.

Event ID 305: Potential Kerberos Restriction Failure

In audit mode, Event ID 305 provides insights into potential Kerberos restriction failures, offering administrators a proactive approach to security monitoring.

Event ID 106: Kerberos Service Ticket Denial

Authentication policies, when enforced, may lead to the denial of Kerberos service tickets. Event ID 106 captures instances where users or devices are restricted from authenticating to a server.

Event ID 306: Potential Kerberos Service Ticket Denial

In audit mode, Event ID 306 anticipates potential Kerberos service ticket denials, offering administrators valuable insights into access control conditions.


Authentication Policy Silos, coupled with meticulous authentication policies, redefine the paradigm of high-privilege access management in Windows Server 2012 R2. This comprehensive guide equips administrators with the knowledge needed to harness the full potential of these security features, ensuring a robust defense against unauthorized access and potential security breaches. Embrace the power of Authentication Policy Silos to fortify your Windows environment and elevate your organization's security posture to new heights.

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