Shouldnt Avast stop such things?
No security program have 100%detection or zero false positives Have you turned on PUP detection (Possible Unwanted Program)

Instructions https://forum.avast.com/index.php?topic=53253.0
Attach Malwarebytes and Farbar Recovery Scan Tool logs … 3 logs total

See below the box you write in … Attachments and other options

when done a malware expert will assist you