Just now my avast detected the filezilla 3.9.0.6 installer as a virus, then I’ve uploaded the file to virustotal for a complete scan with multiple antiviruses, and avast is the only one that finds it a thread: https://www.virustotal.com/en/file/b72c65579bf7e6c8e0c8edbd4056a901aa203eaf43cdef9461084bf1132f0061/analysis/1416174158/
EDIT: downloaded of course from official website/source.