Active Directory: Securing the Crown Jewel Attackers Want Most

Active Directory is very important to attackers in every company. If someone gets control, you lose control of people, files, email, and cloud things. Attackers do not need special hacking skills. They use small mistakes to get full access. You must act fast and take clear steps to protect what is important.

Key Takeaways

• Active Directory helps control who can use your network. Keeping it safe stops attackers from getting important data and systems.

• Check admin accounts often and delete ones you do not need. This makes it harder for attackers to use powerful accounts.

• Set up tiering and segmentation in your network. This keeps attackers from moving around easily and helps stop big problems.

• Turn on Multi-Factor Authentication (MFA) for all admin accounts. This gives extra protection against people who should not get in.

• Watch logs and use security tools to find strange actions. Finding problems early lets you act fast to stop threats.

Why Attackers Target Active Directory

Central Role in Authentication

Active Directory helps decide who can use your network, files, and apps. It is the main guard for most companies. Attackers know this fact. If they get control of Active Directory, they can control almost everything.

Here is a table that explains why attackers want Active Directory:

Active Directory lets you manage all users, computers, and rules in one place. You can set group policies to make rules for everyone. This makes your job easier. But if attackers break in, they can get into everything from one spot.

Consequences of Compromise

If someone takes over Active Directory, bad things can happen. You might lose access to files or services. Attackers can lock you out, steal your data, or stop your business.

Here are some things that could happen:

• Users cannot get to resources or services.

• IT systems might go down and stop working.

• Business tasks may stop, and you could lose money and time.

Tip: Protecting Active Directory is not just about stopping hackers. It also keeps your business working and your data safe.

When you know the risks, you see why attackers want to get into Active Directory. You need to look for weak spots and fix them before attackers do.

Active Directory Attack Paths

Attackers do not need fancy tools to get in. They start small and try to get more control. You need to know each step to stop them early.

Initial Access and Lateral Movement

Attackers often use easy tricks first. They send fake emails to steal passwords. Sometimes, they use passwords that were never changed. They might try common passwords on many accounts. If your network has weak spots, attackers can find them with tools.

After getting in, attackers move to other computers. They use pass-the-hash to steal password hashes. Then, they use those hashes to log in somewhere else. Kerberoasting targets service accounts with weak passwords. Attackers use BloodHound to see your network and find ways to get more power.

Common attack paths include:

• Kerberoasting to break service account passwords.

• LLMNR/NBT-NS poisoning to grab password hashes.

• Using hard-coded passwords in scripts.

• LDAP reconnaissance to learn about users and computers.

Note: Most of these actions look like normal admin work. You need to watch for small clues that something is wrong.

Privilege Escalation Techniques

Attackers want more power after getting in. They use different ways to get higher privileges. Here is a table that shows some common methods:

Domain Dominance Methods

Attackers want total control when they have high privileges. They might make fake tickets called golden tickets. These let them get into anything for a long time. Some use DCSync attacks to copy all password hashes from domain controllers. Others steal the NTDS.dit file, which has every password in your network.

Signs of domain dominance include:

• Ransomware erasing every domain controller.

• Backups that bring back malware when restored.

• No clean backup to use for recovery.

• Attackers stay even after you try to fix things.

• Big mistakes that lock everyone out.

If attackers get this far, they control your whole network. You must stop them before they reach this stage.

Admin Blast Radius Weakness

Excessive Privilege Risks

If too many accounts have high access, it is risky. Attackers search for these accounts. One mistake can give them control. Sometimes, accounts keep their access when not needed. These old accounts are easy for attackers to find. Shadow Admins can hide in your system. They might come from quick fixes or service accounts. These accounts join powerful groups. You may not see them. Group nesting in Active Directory makes them hard to spot.

• Attackers use powerful accounts to get to important things.

• If one admin account is hacked, attackers can change settings, steal data, or install bad software.

• Old admin accounts that are not watched help attackers stay hidden.

Tip: Check admin accounts often. Remove ones you do not need.

Tiering and Segmentation

You can lower risk by splitting your network into layers. This is called tiering and segmentation. It helps you control who can reach important places. When you make separate segments, attackers cannot move easily. Segmentation also stops malware from spreading fast.

• Keeping parts separate limits how far attackers go.

• Segmentation controls who gets into key systems.

• Good segmentation slows down ransomware and other threats.

Quick Wins for Admin Control

You can do simple things to be safer. Start by finding and removing old admin accounts. These accounts are often missed and can be used by attackers. Turn off global admin accounts made for old projects or tools. This quickly makes your network safer.

• Check and remove old admin accounts.

• Turn off global admin accounts for old tools.

Note: Small changes help protect your network a lot.

PKI and Certificate Template Risks

Misconfiguration Dangers

Passwords are not the only thing to worry about. Certificate templates can let attackers sneak in. Weak templates help attackers make certificates that work like master keys. These certificates can give someone admin rights without a password. Attackers call these "invisible" admins. They do not show up in normal logs.

Here is a table that shows common misconfiguration dangers:

Note: Attackers search for weak spots. They want admin rights without anyone knowing.

Securing Certificate Templates

You can block many attacks by making your certificate templates safer. First, check who can enroll in each template. Remove or turn off templates you do not use. Limit access to important templates, like smart card ones.

Here is a table with steps to secure your templates:

Tip: Look at your templates every few months. This helps keep your system safe from new problems.

Practical PKI Actions

You can do easy things to make your PKI stronger. Use an offline root CA to keep your trust anchor safe. Use a domain-joined enterprise CA to give certificates only to trusted users. Set up auto-enrollment with group policy to manage certificates easily.

Here is a table with practical PKI actions:

Remember: Strong PKI settings stop attackers from making invisible admin accounts. Check your templates and permissions often.

Hybrid Sync and Cloud Exposure

Hybrid identity setups link your Active Directory to cloud services. This helps you manage users in both places. But it also brings new risks. If attackers get into your on-premises AD, they can reach cloud accounts. The same thing can happen the other way. A weak cloud account can let attackers into your on-premises AD.

Azure AD Connect Vulnerabilities

Azure AD Connect is a bridge between your local AD and the cloud. Attackers want to control this bridge because it has strong accounts. If someone gets the AD DS Connector or Seamless SSO computer account, they can change passwords or permissions in both places.

Attackers use network tools to attack your whole environment. They can use the AZUREADSSOACC account to move from AD to Entra ID. If attackers get admin rights on the Entra Connect server, they control the Sync Account. They can change identities in both places. Some attackers use SyncJacking to get high-privilege cloud accounts by changing low-privilege accounts.

Tip: Use the lowest-privilege sync account. Watch Azure AD Connect for strange activity.

Conditional Access and MFA

Conditional Access and MFA help protect hybrid setups. Conditional Access rules make users do extra steps, like MFA, before getting in. These rules check things like who you are, your device, and your location. They decide if you should get access.

• Conditional Access uses MFA to keep things safe.

• Rules use signals to make smart choices.

• This follows Zero Trust and checks users every time.

Note: Using MFA for all admin accounts stops many attacks.

Unified Identity Security

You should treat on-premises and cloud identity as one system. Unified security helps you find threats faster and act quickly. Follow these steps to make your defenses stronger:

1. Put Defender for Identity sensors on your domain controllers.

2. Connect Defender for Identity to Microsoft 365 Defender for monitoring.

3. Turn on risk-based Conditional Access in Entra for real-time protection.

4. Use Entra ID Governance to give least privilege to all accounts.

5. Link both to Microsoft Sentinel for better threat detection.

Remember: Strong hybrid identity security stops attackers from moving between on-premises and cloud systems.

Active Directory Security Checklist

A strong checklist helps you protect your network fast. You can use this guide to find and fix the biggest risks in your environment. Start with quick triage steps, then keep your defenses strong with regular maintenance.

60-Minute Triage Steps

You can make a big difference in just one hour. Follow these steps to quickly lower your risk:

1. Check for urgent patches. Install Microsoft’s latest update for CVE-2025-59287 on every WSUS server. This patch closes a major security hole.

2. Block risky network ports. If you cannot patch right away, block inbound TCP 8530 and 8531 at your firewalls. This stops attackers from reaching your WSUS servers. You may need to work with IT because this can pause updates.

3. Stop and disable WSUS services. If you cannot patch or block ports, stop WSUS services until you can fix the problem.

4. Isolate internet-facing WSUS servers. Treat these servers as high risk. Keep them away from your main network.

5. Preserve evidence if you suspect an attack. Save memory, disk images, and event logs. Call your incident response team.

6. Review event logs for changes to AdminSDHolder. Look for event code 5136. This shows if someone changed admin permissions.

7. Check who made changes. Find the user account linked to these changes. Review their activity for anything odd.

8. Compare permissions. Make sure the AdminSDHolder object matches your security baseline.

9. Look for new privileged accounts. Check for changes in group memberships or permissions.

10. Work with your security team. Confirm if any changes were approved.

11. Isolate affected systems. Remove them from the network to stop attackers from spreading.

12. Undo unauthorized changes. Revert any changes to AdminSDHolder that you did not approve.

13. Review all privileged accounts. Make sure they follow your security rules.

14. Reset passwords for at-risk accounts. Focus on admin and service accounts.

15. Add extra monitoring. Watch AdminSDHolder and other key objects for new changes.

16. Tell your security operations center. Let them know about any suspicious activity.

17. Update your access control policies. Make changes to stop similar attacks in the future.

Tip: You can print this checklist and keep it near your desk. Use it when you need to act fast.

Ongoing Maintenance

You need to keep your defenses strong over time. Good habits help you catch problems early and recover quickly.

• Apply updates often. Make sure every patch installs correctly.

• Back up your data on a regular schedule. Test your backups to make sure you can restore them.

• Monitor your domain health every day. Look for signs of trouble, like failed logins or new admin accounts.

• Review admin accounts and group memberships each month. Remove any that you do not need.

• Check your certificate templates and PKI settings every quarter. Remove old templates and tighten permissions.

• Watch your hybrid sync tools, like Azure AD Connect. Look for strange activity or new permissions.

• Train your team to spot phishing and social engineering tricks.

• Schedule regular security reviews. Use your checklist to stay on track.

Note: Small, steady actions keep your network safe. Make these steps part of your routine.

By following this checklist, you build a strong defense around your most important systems. You make it much harder for attackers to break in or stay hidden.

Monitoring and Detection Tools

Key Event IDs and Logs

You need to keep a close eye on your Active Directory. Attackers try to hide what they do. You can find them if you know what to check. Start by looking at important logs and event IDs. These records show changes and help you spot trouble early.

• Group Membership Changes: Watch for strange changes in admin groups. Event ID 4728 means someone added a user to a group. Event ID 4729 means someone removed a user.

• Account Creation and Deletion: Event ID 4720 shows when someone makes a new user. Event ID 4726 shows when someone deletes a user.

• Replication Requests: Event ID 4662 can show odd replication activity. Attackers use this to copy password data.

• Authentication Events: Event ID 4624 logs successful logins. Look for logins at weird times or from new places.

• Group Policy Changes: Event ID 4739 tracks changes to group policies. Attackers may change these to get control.

You should also watch for signs of Kerberoasting or Golden Ticket attacks. These attacks leave clues in your logs, like strange ticket requests or new service accounts.

Tip: Check your logs every day. Quick checks help you catch problems before they get worse.

Recommended Security Tools

You can use special tools to help watch and protect your Active Directory. These tools make it easier to see what is happening and find weak spots.

• Lepide Auditor for Active Directory: Tracks changes in real time and alerts you to suspicious actions.

• Netwrix Auditor: Sends instant alerts and keeps logs for a long time.

• ManageEngine ADAudit Plus: Watches user activity and lets you set custom alerts.

• SolarWinds Access Rights Manager (ARM): Helps you manage who can access what and checks for compliance.

• Quest’s solution: Tracks changes and works with SIEM tools for better monitoring.

• BloodHound: Maps out attack paths so you can see how attackers might move.

• PingCastle: Checks your AD for risks and gives you a health score.

• LAPS (Local Administrator Password Solution): Makes sure each computer has a unique admin password.

• Defender for Identity: Watches for threats and strange behavior on your domain controllers.

Many of these tools work well with SIEM systems like Splunk. This helps you spot attacks faster and respond quickly.

Note: Using the right tools and watching the right logs gives you a strong defense against attackers.

Keeping Active Directory safe helps your business avoid big problems. You protect your network by fixing admin blast radius. You also close PKI loopholes and make hybrid sync better. Attackers move quickly if you miss these steps.

• Watch logs using SIEM tools.

• Give fewer people admin access and change passwords often.

• Use MFA and keep admin computers separate.

• Check group policies and memberships a lot.

Use your triage checklist and check your security every month. Begin with one domain. Make small changes often. Stay watchful to keep your crown jewel safe.

FAQ

What is the most important step to secure Active Directory?

You need to have fewer admin accounts. Make sure each computer has its own password. Check who is in admin groups often. This helps stop attackers from causing big problems.

How often should you review admin accounts and permissions?

Look at admin accounts and permissions every month. Delete accounts you do not use. This makes your network safer and helps you find issues early.

Why do attackers target certificate templates?

Attackers like weak certificate templates. They use them to make fake admin access. These certificates work like secret keys. You should lock down templates and check who can use them.

Can a cloud breach affect on-premises Active Directory?

Yes. If attackers get into cloud accounts, they can reach your on-premises AD. You need to protect both and watch for strange things.

What tools help you monitor Active Directory for attacks?

You can use BloodHound, PingCastle, and Defender for Identity. These tools help you find weak spots and warn you about threats.