It happens from time to time. You are asked to create an account by Human Resources and then the employee never shows up. You would expect HR to tell that the account is no longer needed, right? Worse yet, what if they forget to tell you that the employee was terminated?
Yes, I’ve had to deal with these procedural issues before. From a technology stand point, there is nothing wrong. From a security aspect, everything is wrong. There are two things that you can do to look for these potential problems. The first is to look for accounts that have not been logged into.
Get-ADUser -filter * -Properties LastLogonDate |
Where LastLogonDate -eq $null
The LastLogonDate property became available to us with Windows Server 2003 SP1. Essentially, if the value is $null, then the account has not yet been logged into. You may want to pipe this to Disable-ADAccount. This will stop an unused account from being used.
What about an employee that was terminated, and you were not told? Again, this is a procedural issue that can have serious implications. The first week when I started a job as a Network Administrator, I bumped into a small problem. I had heard through the grape vine that someone was terminated the week before I started. While looking over the security logs, I found out that this person was accessing the system….from the inside. It turns out that his account was not disabled and his key was not taken away. He walked away with a lot of proprietary, confidential data.
Since his account was used, this next command will not help. It will help find accounts that have not been used in a long time.
$Users = get-ADUser -filter * -Properties LastLogonDate
ForEach ($U in (get-ADUser -filter * -Properties LastLogonDate))
If ($U.LastLogonDate -ne $null)
If ((($U.LastLogonDate).Subtract($(Get-Date)) | Select -ExpandProperty Days) -le -60)
Write-output "$($U.Name) has not logged in since $($u.LastLogonDate)"
This will alert you to all accounts that have not be used in 60 days. An alternative is to get rid of the write host line and replace it with:
$U | Disable-ADAccount
That will also shut down those accounts.