I recently wrote a post for Cylance (my employer), discussing the polymorphic features of Qakbot. You can read it here.

About the Author:
Anuj Soni is a Senior Threat Researcher at Cylance, where he performs malware research and reverse engineering. He is also a SANS Certified Instructor and co-author of the course FOR610:Reverse-Engineering Malware. If you would like to learn more about malware analysis strategies, join him at an upcoming SANS FOR610 course.