What is Cookie Hijacking.? Cookie hijacking is also called session hijacking or cookie theft. Cookie hijacking is a hacking process by which the hacker gains unauthorized access to some confidential information in a way which is not facilitated by the user or a secure session. Specifically speaking cookie hijacking means hacking or stealing the cookies that contain confidential information that is needed to authenticate or connect a user to a remote web server. Cookie hijacking can be performed by the hacker by using a computer between the node and server or by obtaining access to the cookies stored on the user’s computer. A hacker can also use source router Internet protocol or IP packets to gain unauthorized access between two communicating nodes. The hacker would then route the packets containing cookies to pass through his computer before reaching destination. Cookie hijacking sometimes is used to perform denial of service attacks also known as DDoS attacks