Why Inactive Computers Pose Security Risks

Security is a crucial element of any infrastructure, and while it may feel like a grind, it’s essential to embrace it. Automation emerges as a powerful ally, streamlining processes, saving time and effort, and eliminating the chaos that human errors can introduce. One vital area where automation excels is in managing inactive Computer Accounts within Active Directory. Disabling these accounts regularly is imperative to thwart potential misuse by malicious actors.

Why Inactive Computers Are a Risk

Inactive computers lurking in your network aren’t just taking up space—they’re potentially opening doors for attackers. Here’s why:

1. Impersonation and Lateral Movement

Attackers can impersonate an inactive computer account if they manage to grab its Kerberos ticket. Using this ticket, they can move around the network with a cloak of anonymity. And if that account is still enabled, lateral movement for attackers becomes much easier.

2. Privilege Escalation

The group membership of a computer object matters—a lot. If a stale computer object is sitting in a high-privilege group like “Domain Controllers,” the consequences could be disastrous. For instance, members of this group have the power to update DNS, modify SYSVOL, and access the NTDS.DIT. Leaving such objects unchecked is like handing over the keys to the kingdom.

3. Shadow IT and Undocumented Devices

An inactive account might be tied to a device that’s no longer in use. But here’s the kicker—an attacker could introduce a similarly configured device to the network and hijack the account credentials, sneaking into your environment unnoticed.

Automate the Cleanup: Enter PowerShell

To make life easier (and more secure), I’ve created a PowerShell script that automates the process of disabling inactive computer accounts in Active Directory. Say goodbye to manual labor and hello to efficiency.

What the Script Does:

• Purpose: It identifies and disables computer accounts inactive for 31+ days.
• Logging: Generates a log of all disabled accounts, saved to C:\Windows\Temp\Logs\InactiveComputers.csv.

Deployment Requirements:

1. Script Location: Save and run the script on a Domain Controller within your environment, I would recommend a folder C:\Scripts as your scripting location!
2. Service Account:
   • Configure the task to run daily under a service account with permissions to read and disable computer objects in Active Directory.
   • Keep the service account’s permissions minimal and avoid direct access to sensitive OUs like Domain Controllers.
3. Task Scheduler:
   • Use Task Scheduler to run the script daily.
   • Test it thoroughly in a non-production environment before rolling it out live.

By automating this process, the script ensures your Active Directory stays clean and secure, addressing stale accounts before they become a problem.

Where to Go

Ready to dive in? Access the script here: DisableInactiveComputers.ps1. Tailor it to suit your environment, and watch as automation handles the heavy lifting effortlessly!

With this approach, you’re not just staying secure—you’re doing it the efficient way. So, what are you waiting for? Get securing!