Exodus 7: 21 And the fish that was in the river died; and the river stank, and the Egyptians could not drink of the water of the river; and there was blood throughout all the land of Egypt. 22 And the magicians of Egypt did so with their enchantments: and Pharaoh's heart was hardened, neither did he hearken unto them; as the Lord had said.
So let us begin by being crystal clear on the matter; apart from raising the dead, and giving life to man, or beast, which is God’s domain and His prerogative alone, satan can work good miracles such as healing the sick, and removing maladies, and diseases from persons in many cases. This he has done on numerous occasions in our day, and persons went away praising God not having any clue as to what transpired.
Again, in the episode of the plagues in Egypt, the devils were able to mimic, in large part the miracles wrought by Moses. Even though in many of those cases, the miracles were not genuine, the counterfeits however were designed to appeal to the five senses of the human agent, to the point where it was virtually impossible to tell the difference, except when Moses’ serpent became hungry and was commanded by God to do lunch.
Exodus 7:10 And Moses and Aaron went in unto Pharaoh, and they did so as the Lord had commanded: and Aaron cast down his rod before Pharaoh, and before his servants, and it became a serpent. 11 Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments. 12 For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods.
Exodus 8: 6 And Aaron stretched out his hand over the waters of Egypt; and the frogs came up, and covered the land of Egypt. 7 And the magicians did so with their enchantments and brought up frogs upon the land of Egypt.
May The Lord add His blessing to the study of His word. God bless!