Hi
packing a virus exe with an unknow packer could confuse avast ?
Sure, just as any other antivirus.
So avast will Not detect packed viruses …
Only if there is used an unknown packing method.
Its like you have RAR file and you want to open it with WinZIP which doesnt support RAR compressed files. You need WinRAR to open RAR file,otherwise its just useless file.