Security

Here’s the scenario…

An executive forwards an email to your ticketing system and asks why they are receiving it. Then sends another from the day before. There is a Microsoft 365 distribution list(DL) in both emails, but not one they would be on. What do you do?

Check and see if there are any tickets for that DL, and you see there haven’t been any tickets for that DL or even that person. You then check the DL, and indeed see they are in it…. but how?

PowerShell to the rescue! Have you ever used “Search-UnifiedAuditLog” which is a cmdlet for Exchange Online PowerShell? It is a great for one off investigations in 365, but here we will use it to find any admin activity for that user in the past week. Full disclosure, I’ve used it a handful of times and had never really dug into which was a mistake on my part. Knowing more of what it can do now would have saved me so much time on other resolutions where I had gone through the 365 portal. Don’t be me, start using this now and create your own functions as well Purview to save you time and headaches. Enable it now, as it can’t be backdated.

# See if you have it enabled
Get-AdminAuditLogConfig | Format-List UnifiedAuditLogIngestionEnabled

# If not enabled, run this
Enable-OrganizationCustomization

# Enable Audit logs - this can take up to 60 mins
Set-AdminAuditLogConfig -UnifiedAuditLogIngestionEnabled $true

Hopefully you already have it enabled, or you enabled it right now and can wait for it to start ingesting the logs so when you do need it, it is available.

Back to our executive incident. How do we find out what happened. The quick way is to run:

# Check for all admin activity for named user
Search-UnifiedAuditLog -StartDate 2/1/2024 -EndDate 3/16/2024 -ObjectIds execuser@domain.com

And this is the way I originally did it to get the answer I needed. That’s it! Then you will see in “AuditData” which groups they were added/removed from and any operations that happened with the groups they are in. This broad search will show even more, but only mentioning parts related to this task. At the end of this post I’ll have a list of great resources on how to get granular on your searches.

Now you can see that another engineer accidentally added them(after confirming with engineer), and you can just remove them from the list. This is best case scenario, as if I hadn’t looked and just removed the executive without searching and asking the engineer, they could have been added by a compromised account seeing what kind of privileges they had.

There is a way clean up the audit data so it is easier to view, but that will be in a longer blog post coming soon. Again, I’ll have some links at the end to give you a head start. Honestly, this was only supposed to be a quick one liner post, that definitely grew, and I’ve spent more time than I would like to admit researching it. It has given me more ideas on how to use it and I’ll put together functions in a repository or possibly a module of most useful commands.

One function I’ll be creating is one to check to see if a user has changed their password recently, has multiple failed attempts, and/or if they have locked themself out. How nice would that be for you or your help desk if the function sees who submitted the ticket, runs the function then gives you that feedback? To go one step farther, if they aren’t blocked out, automatically send them the password reset portal to reset their password?

If you already use this, what scripts/functions have you created? I’d love to hear about them, and I can create a repository for us to keep them in one spot.

Useful Links:

Search-UnifiedAuditLog – Microsoft Learn Cmdlet
How it works – Services that support auditing
Detailed info – Detailed Microsoft Script

Hope this helps saving you from headaches and can’t wait to hear how you use it! Have a great day!