IP hijacking - Definition from the Hotspot Shield Glossary

IP Hijacking is the process of intercepting and controlling a group of IP addresses for malicious purposes. This process is carried out by corrupting internet routing tables - Routers keep a list of up-to-date routing tables that allow them to correctly route data to its intended source.

At the top most level of the internet, the IP addresses are grouped together into prefixes; these prefixes will be created by an AS (autonomous system), with routing tables for these AS’s being maintained by the BGP (Border Gateway Protocol). IP Hijacking involves intercepting BGP transmissions and sessions and posing as one of the parties involved in the session. There have been several incidents of IP Hijacking including TTNet hacking the internet in 2004, a Chinese ISP caused problems in 2010 which stopped many global services, and a Canadian ISP in 2014 came under attack by a hacker that targeted bitcoin operations.