The phrase "demonic attack" refers to a belief in supernatural beings known as demons, who are believed to actively harm or influence individuals in negative ways. Full definition
«This is not to discount the possibility of demonic attacks, but it is to apply caution, in order to ensure that we are best looking after the needs of sufferers.» (premierchristianity.com)
«It needs to be fought in the spiritual realm for it is a demonic attack.» (relevantmagazine.com)