The most common signs of a ransomware attack include: Inability to access files: You might suddenly find that you are unable to open or access your files. Ransom message: Attackers in a ransomware attack usually leave a message on the victim's computer providing instructions on how to pay the ransom that is displayed. Increased network traffic: You might observe a sudden increase in outbound traffic where the attacker might have already gained access to a victim's system and is communicating with their servers. Unusual activity: You might notice unusual activities, such as numerous files being encrypted. Denied access: You might be denied access to your computer.