Active Directory Security Explained & 7 Active Directory Best Practices 

What is Active Directory?

Active Directory (AD) is a Microsoft Windows directory service allowing IT administrators to manage users, applications, data, and various other aspects of their organization’s network. Active Directory security is vital to protect user credentials, company systems, sensitive data, software applications, and more from unauthorized access. A security compromise of AD can essentially undermine the integrity of your identity management infrastructure, leading to potentially catastrophic levels of data leakage and/or system corruption/destruction.

Why It Is Critical to Secure the Active Directory System

Since AD is central to authorizing users, access, and applications throughout an organization, it is a prime target for attackers. If a cyber attacker can access the AD system, they can potentially access all connected user accounts, databases, applications, and all types of information, jeopardizing security for an entire AD forest. Therefore, an Active Security compromise, particularly those not caught early, can lead to widespread fallout from which it may be difficult to recover.

Threats to Active Directory Systems

Let’s delve into several key areas where Active Directory systems may be susceptible to threats:

• Default Security Settings: AD has a set of predetermined, default security settings created by Microsoft. These security settings may not be ideal for your organization's needs. Additionally, these default security settings are well-understood by hackers, who will try to exploit gaps and vulnerabilities.
• Inappropriate Administrative Users and Privileged Access: Domain user accounts and other administrative users may have full, privileged access to AD. Most employees, even those in IT, do not need high-level or superuser privileges.
• Inappropriate or Broad Access for Roles and Employees: AD allows administrators to grant access to specific applications and data based on employee roles. Roles are assigned to groups with different access levels. It’s important to only allow the levels of access individuals and roles need to perform their job functions.
• Uncomplex Passwords for Administrative Accounts: Brute force attacks on AD services often target passwords. Uncomplicated passwords and easily guessable passwords are most at risk.
• Unpatched Vulnerabilities on AD Servers: Hackers can quickly exploit unpatched applications, OS, and firmware on AD servers, giving them a critical first foothold within your environment.
• Lack of Visibility and Reporting of Unauthorized Access Attempts: If IT administrators have awareness about unauthorized access attempts, they can more effectively disrupt or prevent such access attempts in the future. Thus, a clear Windows audit trail is vital to identify both legitimate and malicious access attempts, and to detect any changes in AD.

Active Directory Security Best Practices

There are at least 7 active directory security best practices IT departments should implement to ensure holistic security around Active Directory:

1. Review and Amend Default Security Settings

After installing AD, it's vital to review the security configuration and update it in line with business needs.

2. Implement Principles of Least Privilege in AD Roles and Groups

Review all the necessary permissions for data and applications for all employee roles in the organization. Ensure employees have only the minimal level of access they need to perform their roles. Also ensure separation of privileges, so there is tighter auditability between roles and to help prevent lateral movement in the event an account is compromised. Apply strong privileged access management (PAM) policies and security controls.

3. Control AD Administration Privileges and Limit Domain User Accounts

Carefully review all IT staff and only provide administrative privileges and superuser access to those who absolutely need this access to perform their roles. Use PowerShell Just Enough Administration (JEA) and/or a PAM solution to ensure this access is limited in the most granular way practical. Ensure these accounts are properly protected with robust passwords.