You might think your Active Directory setup is secure. Most IT teams do. But even with the best intentions, it’s easy to overlook small details. And when it comes to AD, small mistakes can lead to big problems—like breaches, downtime, or lost trust.
The good news? Most of these issues are fixable. But first, you have to know they exist. Let’s walk through some of the most common Active Directory security mistakes that often go unnoticed—and how to correct them before they cause trouble.
Overlooking Secure Communication Protocols
This one seems obvious, but it still trips people up. AD environments often run on default settings. That includes using protocols like LDAP without encryption. If your directory services are exposed to the network in plain text, that’s a major risk.
You want to make sure you’re using LDAPS, which encrypts traffic between clients and domain controllers. Same goes for DNS. If you haven’t enabled DNSSEC, it’s time to look into it. These small steps go a long way in securing your environment.
And here’s where it gets serious. Without encrypted protocols in place, attackers have a better chance of intercepting your data. That’s how man-in-the-middle attacks happen. When you secure communication across your systems, you help prevent man in the middle attacks that could let someone capture credentials, inject malicious commands, or impersonate users.
Just because something “works” doesn’t mean it’s secure. Take the time to double-check how your systems talk to each other. Encrypted communication is one of the easiest wins in AD security.
Letting Old Accounts Linger
Inactive accounts are easy to forget. Maybe an employee left the company six months ago. Or a temp account was created for a short-term contractor. If those accounts are still active, they can be a huge weak spot.
Attackers often look for these forgotten accounts. Why? Because no one’s watching them. If they get in, they can move around your network with little resistance.
Make it a habit to review your AD users list. Disable accounts that haven’t been used in 30 or 60 days. Better yet, automate the process so that inactive accounts are flagged or disabled after a set period. Keeping your directory clean is just good hygiene.
Using Broad Permissions Too Freely
Not everyone needs Domain Admin rights. But you’d be surprised how often users have more access than they need. Maybe someone got elevated permissions during a project—and no one removed them after.
This is risky. The more people with high-level access, the easier it is for attackers to gain control if they compromise one of those accounts.
Stick to the principle of least privilege. Give users only the access they need to do their jobs. Nothing more. And don’t forget to review group memberships regularly. Clean them up and make sure everyone’s in the right place.
Ignoring Delegation Settings
Delegation is a useful feature in AD, but it can also be dangerous—especially if you’re using unconstrained delegation. This setting allows services to act on behalf of users, which is helpful in some workflows. But it also gives attackers a way to impersonate users if they gain access.
You should avoid unconstrained delegation whenever possible. If you absolutely need it, monitor it closely. Use constrained delegation instead, which limits what a service can do.
Also, audit delegation settings regularly. Tools like Microsoft’s native auditing features or third-party tools can help you spot risky configurations before someone else does.
Failing to Monitor Changes in Real-Time
If someone adds themselves to a security group or changes a GPO, would you know right away? Many teams wouldn’t.
That’s a problem. AD is the core of your environment. Any change—especially unauthorized ones—can have serious effects. That’s why you need real-time monitoring in place.
Set up alerts for critical actions. You want to know when an account is locked out, when group memberships change, or when key configurations are updated. The faster you know about it, the faster you can respond.
Skipping Regular Security Audits
Audits aren’t exciting. But they’re necessary. Without regular audits, it’s hard to know what’s working, what’s outdated, or what’s just plain wrong.
Old group policies, unused service accounts, open shares—these things pile up. And they often go unnoticed until something breaks or an attacker finds a way in.
Schedule audits at least once a quarter. Look for unusual activity, outdated settings, and anything that seems out of place. Use checklists or tools to help guide you through it. Even a simple review can uncover major issues.
Relying on Weak Password Policies
Passwords are still one of the biggest targets for attackers. And yet, many AD environments still rely on weak or outdated password policies.
Short passwords, reused passwords, or never-expiring passwords—they’re all dangerous. If attackers get hold of one, they could have access for months without anyone noticing.
Set a strong password policy. Enforce complexity and expiration. Encourage users to use passphrases instead of short passwords. And where possible, enable multi-factor authentication (MFA). It’s one of the best defenses you can implement.
Also, consider using protected user groups for sensitive accounts. These built-in groups come with extra security protections and can reduce your attack surface.
Assuming Backups Are Always Working
Backups only help if they work. And too often, admins assume everything’s fine—until it’s not.
You need to test your backups. Not just once, but regularly. Can you recover your AD from scratch? Do you know how long it would take? What would happen to your users during that time?
Also, make sure your backups are secure. Don’t store them on the same network as your production systems. If ransomware hits, you don’t want your backups getting locked up too.
AD recovery is tricky. Make sure your plan is solid and everyone on your team knows what to do.
It’s easy to focus on the big stuff—firewalls, antivirus, threat intel. But Active Directory is often the core of your entire infrastructure. If something goes wrong there, everything else feels it.
That’s why it’s so important to look at the details. The small oversights. The everyday habits. The things you assume are fine.
By cleaning up inactive accounts, locking down permissions, using secure communication, and auditing regularly, you build a stronger foundation. These aren’t huge tasks, but they make a huge difference.
And in the world of cybersecurity, staying one step ahead is everything. You don’t have to be perfect. You just have to be prepared.
