The main thing is to make sure that Veil or any other framework that you’re using to generate the backdoor is up to date. Here are some few solutions to try if your backdoor is getting detected:
1. Make sure that you have the latest version of Veil, so do <i>updated</i> before doing use 1.
2. Experiment with different payloads, and experiment with different payload options and you should be able to bypass it.
3. Try generating a backdoor using the TheFatRat, Empire, or Phantom Evasion
4. Modify backdoor code if its in bat (covered in the Social Engineering course)
5. Modify backdoor using a hex editor (covered in the Social Engineering course)
6. Create your own backdoor (covered in Python course) which is one of the best ways to make the backdoor signature looks more unique and increase the chances of bypassing more AVs
You can check the last lecture of the course (bonus lecture) it contains all the courses that you can take with this course and a comparison between them.