In short, free tools like free FUD crypter don’t update their core due to last antivirus detections. You can watch antivirus bypass videos that use free tools, but they can’t help you on Runtime or while your file is running.
Updated tools like Warzone RAT, update its core and modules for best FUD results. If you don’t know what is remote access trojans read our blog posts.
Do you need to make crypter software? We recommend testing the free FUD crypter GitHub and downloading it. Be careful of backdoors and test on VMware, and find how to encrypt the RAT trojans or other malware. So, your RAT bypass windows defender.
Then buy FUD crypter and test again. Read more about process hollowing and PE Injection methods or polymorphic crypter for more information.