What I learnt today: Mandatory User Profiles
Praetorian named their blog "Persistence Through Forgotten Windows Internals", and true, at least I never heard of Mandatory User Profiles before reading this article.
In enterprise environments, administrators sometimes want to enforce a specific user profile that resets on each login. To accomplish this, Windows supports a file called NTUSER[.]MAN (the .MAN standing for “mandatory”), which takes precedence over the usual NTUSER.DAT registry hive stored in %USERPROFILE% when a user logs in.
Setting up persistence on a copy of NTUSER.DAT using the Offline Registry Library might evade some EDRs. The whole blog post is worth a read, but the TL;DR for defender is:
Consider monitoring for NTUSER[.]MAN file creation in user profile directories, especially when it doesn’t come from an enterprise profile management system.
Source:
https://praetorian.com/blog/corrupting-the-hive-mind-persistence-through-forgotten-windows-internals/