What is Active Directory Security? Risks and Best Practices

UPDATE: This post, originally published on May 3, 2024, has been revised to reflect expanded coverage of Active Directory security risks, updated best practices aligned with recent threat intelligence, and new guidance on leveraging Tanium for Active Directory visibility and control.

Active Directory (AD) is a Microsoft Windows service that stores, manages, and centralizes access controls for domains, applications, groups, user accounts, and endpoint devices. While originally developed for Windows environments, many organizations now extend it to manage access for Linux and macOS systems through third-party integration tools.

As more organizations shift IT operations to the cloud, Microsoft has also released Microsoft Entra ID, formerly Azure AD, a cloud-based version of Active Directory that provides network and identity and access management (IAM) for both cloud and traditional on-premises environments.

One reason Active Directory is so popular is its scalability. The directory service allows organizations to manage access controls and enforce security policies in a flexible, scalable manner from tens of thousands of users to a single remote device.

Unfortunately, due to the critical role Active Directory plays in authentication and authorization, it has also become a tempting target.

This blog post explores key aspects of why securing Active Directory is so critical, how attackers commonly exploit it, and what you can do to defend against breaches. You’ll learn about the most common missteps that leave AD vulnerable, the evolving threat landscape, and the foundational best practices to harden your environment—while keeping your organization productive and agile.

We’ll also show how modern features and tools like AI and Autonomous Endpoint Management (AEM) are transforming AD security by giving IT and security teams the visibility, automation, and control they need to stay ahead of attackers.

• Active Directory architecture and security: What you need to know
• Why is securing Active Directory important?
• What are common Active Directory security risks?
• 5 Active Directory security best practices
• How Tanium extends visibility and control beyond native AD tools
• Active Directory security FAQ

Active Directory architecture and security: What you need to know

To better understand the needs of AD security, it’s helpful to understand its structure. Active Directory uses the concept of domains, forests, and trees to organize access controls and streamline managing user and device accounts:

• A domain is a sub-structure within an Active Directory environment that houses objects on a network like users, computers, and groups within a common authentication database.
  
  Domains rely on specialized servers known as domain controllers (DCs) that consolidate storing and managing object information and user authentication requests in one place. Security groups, organizational units (OUs), and group policy objects (GPOs) are standard methods used at the domain level to streamline administrative tasks.
• A tree is a structured, tiered arrangement of one or more domains within Active Directory.
  
  In an enterprise network, numerous users and individual trees can consist of multiple domains or subdomains, all originating from a root domain. The root domain in Active Directory is the “root” of the tree structure and sets the standard for naming conventions across a forest.
• A forest is a collection of one or more domain trees that share schemas, configurations, and global catalogs, allowing for centralized management of multiple domains.
  
  Each forest also acts as a security boundary, and domain trusts must be carefully configured to avoid unintended access between forests. This means that for objects in separate Active Directory forests to interact with one another, trust must be established by the administrators overseeing each respective forest. Without this trust, interaction between the objects across forests is not possible.

Here’s a quick breakdown of how these components work and why they matter for security:

AD component	Description	Key security implication
Domain	Sub-structure housing users, computers, and groups	Centralized authentication and policy enforcement
Tree	Hierarchical arrangement of domains	Inherits naming and trust from root domain
Forest	Collection of domain trees with shared schema	Acts as a security boundary requiring trust relationships

With this overview of the AD structure, you can see how managing Active Directory can become quite challenging and increasingly complex. Organizations must manage and maintain Active Directory to ensure that the right users, devices, and services have the appropriate levels of access because all it takes is one misconfiguration to hand attackers the keys to your IT kingdom.

This complexity—and the potential for missteps—is precisely what makes Active Directory such a high-value target.

Back to table of contents

Why is securing Active Directory important?

Active Directory is the backbone of enterprise identity. It authenticates users, authorizes access, and governs permissions across nearly every endpoint, application, and service in your environment. That centrality makes it indispensable and dangerously attractive to attackers, regardless of their ultimate objective—whether it’s a massive data breach, the deployment of ransomware, intellectual property theft, or other forms of malicious behavior aimed at disrupting business operations.

Active Directory is frequently described as the “keys to the IT kingdom” because it serves as the central repository for credentials and manages access controls for virtually every endpoint, application, and service within an organization.

That’s why AD is often the first target in sophisticated attacks. It holds the user credentials, the access paths, and the control levers that adversaries need to move laterally, escalate privileges, and take over systems.

While AD streamlines IT operations and simplifies user management, its power also makes it a single point of failure. A breach here doesn’t just affect one system—it can lead to widespread system disruptions across the organization.

Why attackers target AD

• It stores centralized credentials
• It governs access to critical systems, services,
  endpoints, and data
• It’s often misconfigured and under-monitored

And the threat isn’t theoretical. Industry reports show that a significant percentage of organizations have experienced attacks that specifically targeted AD. Once compromised, attackers can exploit service accounts, elevate privileges, and exfiltrate data—often without triggering alarms.

The result? Downtime, data losses, reputational damage, and regulatory fallout.

So how do you protect something this powerful and vulnerable? Let’s start with the most common ways attackers exploit AD—and the missteps that make it easier for them.

Back to table of contents

What are common Active Directory security risks?

Active Directory environments are susceptible to a range of security risks, including misconfigurations, credential theft, and privilege escalation. Attackers frequently exploit these vulnerabilities to gain unauthorized access and move laterally across networks.

As the NSA and CISA determined, many AD-related incidents stem from poor cyber hygiene practices that could have been prevented with stronger foundational practices.

Microsoft emphasizes the need to address these potential weaknesses in a recent report, identifying several high-impact vulnerabilities that organizations should prioritize to strengthen their Active Directory and identity infrastructure:

• Lack of adequate protection for local administrative accounts
• A broken security barrier between on-premises and cloud administration
• Lack of adherence to the least privilege model
• Legacy authentication protocols
• Insecure Active Directory configurations

This list also illustrates how seemingly minor or outdated components—like legacy services and unsupported protocols—can quietly persist in enterprise environments and become easy entry points for attackers. For example, legacy services such as the print spooler can introduce vulnerabilities if not properly secured or disabled. Likewise, outdated protocols like SMBv1 should be disabled to reduce exposure to known exploits.

To help you quickly identify where your organization might be exposed, here’s a snapshot of some of the most common Active Directory security risks:

Risk	Description	Example
Weak/default passwords	Easy entry point for attackers	Default admin credentials
Excessive privileges	Users inherit unnecessary access	Domain users adding workstations
Patch mismanagement	Unpatched systems vulnerable to exploits	Delayed Windows Server updates
Policy conflicts	Domain vs. local policy issues	Overridden security settings

We’ll explore each of these risks in more detail below to provide a clear explanation of how they impact AD security, including what they look like in practice, how attackers exploit them, and why they matter.

Using weak and default passwords

Using a weak password for the Active Directory administrator account or any other key account makes it easier for attackers to break in. Once inside, they can attempt to escalate privileges, create new accounts to gain more access, and even change permissions or delete accounts to halt operations by shutting employees out from business-critical services.

Additionally, using default passwords can eliminate time and guesswork for attackers, giving them speedy and likely undetectable access to valuable resources. Since Active Directory comes configured with default passwords set up by Microsoft, administrators should take the time to change default passwords for Active Directory and all their applications, services, and devices.

User accounts with incorrect privilege levels

Remember that user accounts inherit the privileges of their groups. Regularly reviewing access privileges can help ensure that Active Directory users are not being granted privileges beyond those necessary for their jobs simply because they belong to a certain group. For example, domain user accounts can add workstations by default, meaning attackers with these compromised credentials can add personal computers to more easily access your environment.

Another example of attackers leveraging AD accounts is Kerberoasting, which gets its name from Kerberos—an authentication protocol used by Windows to authenticate services on untrusted networks. Attackers first compromise a user account using phishing, keylogging, a memory scraping tool like Mimikatz, or some other technique to gain login access. Once logged in, the attacker looks for Active Directory service accounts with Service Principal Names (SPNs) enabled.
 
Service accounts are often targeted due to the elevated permissions granted to them, as organizations tend to set up these accounts with high-level domain privileges to ensure users have uninterrupted access to the resources they need. The attacker then requests tickets from the Kerberos Ticket Granting Service (TGS), which returns encrypted, hashed versions of the passwords for the accounts the attacker can extract and work offline to crack. In short, attackers can trick AD into handing over encrypted credentials they can later decode.

If successfully breached, attackers have a wide range of options—they can escalate privileges, which use one account to obtain more privileged access to other resources within the network. Attackers can also install ransomware that spreads quickly across the organization, causing system disruptions, halting business operations, and causing irreparable data loss.

The balance between enforcing policies to maintain AD security and ensuring that users have the necessary access to perform their duties is delicate. If not managed properly, this can lead to security gaps and IT compliance issues that make the organization vulnerable to security breaches.

Insufficient policy and patch management

Like all enterprise software, Active Directory needs to be updated occasionally to improve performance and fix recently discovered security vulnerabilities. Failing to patch Active Directory in a timely manner leaves it exposed to software vulnerabilities that attackers can exploit. It is also critical to ensure Windows Server operating systems and other software are up to date.

[Read also: Risks and mitigations of unpatched software]

Conflicting Active Directory and local policies can also create complications. For example, if an endpoint is joined to a domain and receives a domain policy that contains the same policy setting that a local policy is trying to apply, the domain policy will take precedence, which can lead to management challenges.

Attackers often exploit misconfigurations to trick Active Directory into issuing fraudulent certifications or escalating the privileges granted to include administrative privileges. Like Kerberoasting, these attacks are difficult to detect since the actions appear to be issued legitimately, allowing attackers longer dwell time in environments and more opportunities to cause damage.

You don’t have to choose between security and agility. These five foundational best practices show how to defend against today’s threats while keeping your environment flexible.

Back to table of contents

5 Active Directory security best practices

Securing Active Directory isn’t about restricting access—it’s about enabling the right access for the right people. These foundational practices are proactive security measures that help you strike that balance. By implementing them, you can harden your AD environment against cyber threats and strengthen your overall security posture across domains, user accounts, and IT resources.
By following these AD security best practices, organizations can help keep Active Directory and all the domains, user accounts, and IT resources it controls more secure.

1. Embrace Zero Trust and multi-factor authentication (MFA)

   A Zero Trust approach, complemented by mandatory multi-factor authentication, ensures that no user or device is inherently trusted, requiring continuous verification before granting access.
   

   Zero-Trust security means that users and devices are afforded zero trust by default and are not trusted until verified.

   Users are granted access rights in compliance with the principle of least privilege only after verification.

   Applying the principle of least privilege when configuring access controls for accounts, whether for users or services, gives users the access privileges they need to do their jobs—and nothing more.

   For example, if a user needs read access to a finance application for their job, the principle of least privilege would mean they’re only given access to that specific application and not every business application to guarantee that attackers will have as little access as possible if they manage to take over the account.

   Download the Tanium for Zero Trust solution brief to
   learn how to build your Zero Trust foundation with
   real-time visibility and control

   Multi-factor authentication is also essential to implementing Zero Trust. MFA requires anyone accessing an account to use a password and a secondary authentication method, such as a randomly generated numerical key delivered by text, email, or an encrypted digital signature stored on a hardware key. Requiring multi-factor authentication can make it more difficult for attackers to gain access to AD using compromised user accounts.

2. Enforce strong password policies

   Implementing strict password policies, including complexity, length, and regular rotation requirements, serves as a foundational defense against credential-based attacks. Even with MFA and Zero Trust in place, no system is foolproof.

   Strict password policies remain a critical defense mechanism for bolstering Active Directory security and act as additional safeguards, ensuring that even if other security layers are compromised, the integrity of Active Directory remains intact.

   Many modern password policies require complex passwords containing upper- and lowercase letters, numbers, and symbols. Strong passwords should also be at least 12 characters long, though Microsoft recommends that 14 or more is even better.

   Consider using randomly generated passwords from password managers rather than passwords composed of common words with numbers and symbols thrown in. Additional types of password policies organizations can implement include password expirations, lockout policies, and blocking commonly used passwords known to be vulnerable.

To mitigate and protect against [security gaps and attack vectors like insecure Active Directory configurations], we recommend randomizing local administrative account passwords, not synchronizing on-premises administrative accounts to the cloud, and having separate accounts and purpose-built hardened workstations for on-premises and cloud administration.¹

3. Reduce the attack surface with proper user account management

   Diligently managing user accounts, including timely deprovisioning and limiting administrative privileges, significantly minimizes the pathways attackers can exploit within an Active Directory environment.

   Attack surfaces continue to expand as endpoints multiply and teams adopt multi-cloud strategies. With a compromised account, attackers can successfully move from one endpoint to another or use vulnerable network ports to conduct attacks, a process called lateral movement.

   Active Directory monitoring is essential for uncovering misconfigurations, privilege escalations, and potential attack paths before they can be exploited. By proactively monitoring endpoints, mapping likely attack vectors, and understanding user roles, permissions, and access levels, organizations can strengthen their AD defenses. Enhancing user account security settings to limit lateral movement—should an attacker gain access—further reduces the risk of widespread compromise.

   [Read also: What is endpoint security? Benefits, types, and best practices]

   Another opportunity to shrink the attack surface is promptly deleting accounts if a user, especially a user with a privileged account, leaves your organization or changes jobs.
   
   This can help eliminate the risk of attackers taking over or compromising unused accounts. Limiting the number of domain admins and enforcing strict privilege access controls in an Active Directory environment can also help minimize your attack surface.
   
   Since domain administrators have the power to create and configure access rights for accounts and are usually members of the administrator group on all domain controllers, the potential for a domain to be compromised increases as the number of users in privileged security groups grows.

4. Keep your systems patched, updated, and backed up

   Regular patching, system updates, and comprehensive backup strategies are crucial for maintaining Active Directory’s integrity, ensuring business continuity, and mitigating the impact of security incidents.
   

   If Active Directory goes down, users across the organization lose the ability to authenticate themselves. Setting up a backup server for your Active Directory domain can allow you to fall back and restore access privileges to ensure the continuation of daily business operations if your primary server has an outage or is compromised in a cyberattack.

   Establishing a formal recovery plan for your AD server and testing it regularly can also help you ensure everything works or will work properly when a security incident occurs.

   Another best practice is to ensure all systems are consistently kept up to date with the latest security patches. This proactive approach significantly reduces the risk of exploitation by addressing known vulnerabilities and fixing security issues as soon as they’re discovered or disclosed.
   
   Timely patching helps prevent security breaches that could compromise the availability, integrity, or confidentiality of Active Directory services, which often serves as the backbone of enterprise identity, access management, and overall IT infrastructure.
   
   Through updates and effective patch management, organizations not only strengthen their security posture but also maintain compliance with industry regulations and internal standards that mandate a minimum level of protection for sensitive systems and data.

5. Evolve your layered security strategy with AI

   Modern threats move fast—and adapt even faster. That’s why a layered security approach is no longer just about stacking traditional defenses like firewalls and account lockouts. Today, organizations are evolving their strategies by integrating AI as a foundational layer—one that brings speed, scale, and intelligence to AD protection.

   Employing multiple cybersecurity solutions and strategies across different attack vectors provides a comprehensive defense, enhancing Active Directory’s resilience against diverse threats. AI strengthens this approach by helping detect subtle anomalies, automate repetitive tasks, and accelerate response times—especially in complex environments like AD, where speed and precision are essential.

   The harsh reality is that no single cybersecurity solution can combat all modern threats. Instead, organizations can better protect their directory services by layering multiple security controls that address different attack vectors. For example, implementing firewalls—such as DNS or Windows firewalls—helps control both inbound and outbound traffic, ensuring only essential communication is permitted and reducing the risk of unauthorized access.

   You can also deploy tools that detect Active Directory-focused attack types, such as brute force password attempts. In these attacks, adversaries use scripts to rapidly test password combinations in hopes of gaining access.
   
   Domain administrator accounts and other privileged credentials are common targets. If even one guess succeeds, attackers can gain a foothold in your environment.

   To mitigate this risk, organizations should implement account lockout policies that trigger after a set number of failed login attempts. These controls, combined with alerting mechanisms, can help detect and contain brute force attacks before they escalate.

   AI also plays a critical role in improving IT automation. From triggering account lockouts to isolating suspicious user activity across endpoints during security events, AI-driven automation reduces the time between detection and action—helping teams contain threats before they spread.

   AI holds the potential to be as much of a transformative technological revolution for human beings as things like electricity or modern computing… But, as we’ve seen repeatedly throughout the course of history, when in the wrong hands, any sufficiently new and powerful tool… can be used to cause harm.²

   This duality makes it clear: AI is not a replacement for layered security—it’s a force multiplier. When integrated thoughtfully, it empowers organizations to anticipate threats, respond faster, and reduce risk before damage is done.

[Read also: What is security automation?]

It’s important to recognize that selecting the right Active Directory security tools should be based on a clear understanding of your organization’s specific needs. Their effectiveness depends not only on the current threat landscape but also on how well they align with your objectives, risk profile, regulatory requirements, and operational realities. Performing a thorough business needs assessment and determining your cyber risk score are critical steps in implementing the most appropriate and impactful AD security strategies.

However, even with the right policies in place, visibility is everything. You can’t secure what you can’t see.

That’s where Tanium comes in—delivering real-time visibility and AI-powered control across every endpoint.

Back to table of contents

How Tanium extends visibility and control beyond native AD tools

Fortifying Active Directory security isn’t optional—it’s foundational. As we’ve seen, the risks are real, and the consequences of a breach can be catastrophic. That’s why visibility and control aren’t just helpful—they’re non-negotiable. It’s a type of security where the details matter, and simply granting a user the wrong set of access privileges could allow attackers access to your organization’s most valuable assets.

To outpace evolving threats, IT, security, and operations teams must remain vigilant. That means continuously monitoring for vulnerabilities, diligently adhering to AD security best practices, and having the right tools and platforms in place to detect, respond to, and prevent attacks before they escalate.

Want a deeper look at how Tanium’s AI-powered platform supports real-time visibility and control? Explore how Tanium AEM can help you reduce risk and respond faster

However, gaining a comprehensive view of Active Directory status, local user accounts, and group memberships across thousands of endpoints can pose a significant challenge. Traditional direct query approaches can overwhelm Active Directory infrastructure with simultaneous requests.

Tanium’s AI-driven platform enhances this vigilance with intelligent automation and autonomous endpoint management. By combining real-time monitoring, automated enforcement, and unified visibility across endpoints, Tanium empowers organizations to shrink their attack surface before attackers exploit it and improve overall security management through real-time visibility and control. It’s not just about visibility—it’s about taking swift, intelligent action.

One way Tanium supports Active Directory visibility is through Directory Query. Directory Query works with Tanium Criticality and Impact to help organizations understand administrative rights within their directory server environments to provide foundational visibility that supports broader security and compliance workflows.

For organizations seeking to understand administrative relationships and access rights, using a solution like Tanium Incident Response provides visibility into privileged accounts and group memberships—helping teams identify and reduce unnecessary access, especially on high-value assets.

Additionally, Tanium Risk & Compliance continuously monitors for vulnerability and compliance gaps across both managed and unmanaged endpoints, enabling organizations to maintain a strong security posture and meet regulatory expectations.

This cohesive platform doesn’t stop at internal visibility—it extends into the cloud by integrating directly with identity providers like Microsoft Entra ID (formerly Azure AD). This connection delivers real-time insight into user and group relationships, administrative rights, and potential misconfigurations across hybrid environments.

See how Tanium integrates with Microsoft to enhance identity visibility, streamline access control, and support real-time security operations.

What sets Tanium apart is how our solutions are designed to work seamlessly together—and how we unify internal capabilities with external integrations, like Microsoft Entra ID, to deliver end-to-end visibility, compliance, and privilege analysis across your entire environment. This cohesive approach enables IT and security teams to protect assets, investigate threats, and fine-tune AD security without switching tools or sacrificing speed.

Back to table of contents

Active Directory security FAQ

Not sure where to start? You’re not alone. These are the questions we hear most often from teams looking to secure their AD environment.

What is the main authentication protocol used by Active Directory?

Active Directory primarily uses the Kerberos authentication protocol to verify user identities and grant access to network resources. It also supports NTLM (NT LAN Manager) for compatibility with legacy systems, though Kerberos is the preferred and more secure method due to its use of encrypted tickets and mutual authentication.

Is Active Directory a security tool?

While Active Directory isn’t a dedicated cybersecurity tool in the traditional sense, it plays a critical role in an organization’s overall security posture. As the central authority for identity and access management, AD governs who can access what across the network—making its security essential to protecting systems, data, and users. In that sense, it’s not just part of your infrastructure—it’s a core pillar of your security strategy.

What is least privilege security in Active Directory?

Least privilege security is a core principle in Active Directory that ensures users and systems are granted only the minimum access necessary to perform their specific job functions—nothing more. This approach reduces the risk of misuse or exploitation and limits the potential damage if an account is compromised.

What is the difference between Azure AD and Active Directory security?

The key difference lies in their architecture and operational scope. Traditional Active Directory (AD DS) is designed for on-premises environments, managing local users, computers, and resources within a Windows domain. Azure AD—now Microsoft Entra ID—is a cloud-based identity and access management service built to manage users and access to SaaS applications, cloud services, and hybrid environments.

While both platforms manage identities, their security models differ in terms of infrastructure, threat exposure (e.g., Azure AD is internet-facing), and built-in capabilities—such as conditional access, identity protection, and integration with cloud-native security tools in Azure AD.

How do I check Active Directory security?

Conducting a regular security assessment of Active Directory involves a multi-faceted approach. This includes auditing logs for suspicious activity, reviewing Group Policy Objects for misconfigurations, checking for weak or default passwords, identifying over-privileged accounts, and ensuring all systems and AD components are consistently patched and updated.

Specialized tools—such as the Microsoft Defender suite, Tanium, and others—can automate many of these checks, streamlining the security assessment process through capabilities like auditing, privilege analysis, and misconfiguration detection.

Back to table of contents

---

Improving your ability to manage threats, risk, and compliance is a key component of our vision for Autonomous Endpoint Management—the next evolution of the Tanium platform. It combines pre-configured playbooks, seamless platform integrations, AI-driven insights, workflows, and the ability to automate remediations through real-time control and visibility to unify IT operations and security teams.

Want to see how Tanium can help you harden AD without slowing down your team? Schedule a free, personalized demo to learn how Tanium AEM can provide unmatched operational efficiency and risk mitigation capabilities.