Question: "Does Satan have to get God's permission before he can attack us?"
Answer: There is no biblical evidence that suggests Satan needs God's specific permission in order to act against Christians. Many people believe that Job 1 supports the idea of Satan not being able to afflict Job until he asked God. However, consider Satan's argument before God, "Have you not put a hedge around him and his household and everything he has? You have blessed the work of his hands, so that his flocks and herds are spread throughout the land" (Job 1:10). Satan is obviously familiar with who Job is and is aware of Job's special protection and blessing by God. How could Satan have known of Job's protection, unless he and/or his demonic minions had not already tried to work their will against Job? What Satan is really asking is for God to remove Job's protection.
A similar passage is Luke 22:31-32: "Simon, Simon, Satan has asked to sift you as wheat. But I have prayed for you, Simon, that your faith may not fail. And when you have turned back, strengthen your brothers." Clearly in this case Satan had to ask permission to tempt Peter. Jesus tells Peter that He has prayed specifically for him so that Peter can strengthen the other disciples, the implication being that the others WILL be sifted in whatever way Satan intends. The Bible does not specifically state that the disciples had special protection from God, but there is no doubt that God had a higher purpose in mind—the strengthening of the other disciples—in allowing Satan to harass Peter.
Whereas these passages imply that there are boundaries and rules Satan must abide by, there is no real biblical proof that he needs God's permission. The very character of Satan proves that he disdains authority and is not one who would truly seek permission. Job was hedged about by the Lord—Satan couldn’t get to him without the Lord first removing that protection. The ultimate reality is that God controls everything in the universe, including Satan, and that “in all things God works for the good of those who love him, who have been called according to his purpose” (Romans 8:28).