I'm learning malware analysis. I'm looking for malware samples that terminate themselves when recognize working on a VM or sandbox.
For learning purposes, I would recommend you the following Github projects to start with:
Paranoid Fish by a0rtega
Al-Khaser v0.60 by Noteworthy
Colection by AlicanAkyol
Grab one you like, compile and analyze.
In case you look for in the wild samples, you should look at Andromeda\Gamarue bot. It have a plenty of anti tricks, including anti-VM, anti-Sandbox, anti-research etc.