A security researcher has developed a new attack for a well-known flaw in the TCP protocol that allows an attacker to effectively shut down targeted routers and terminate existing TCP sessions at will. The scenario has many security experts worried, given the ubiquity of TCP and the fact that there's an attack tool already circulating on the Interne
The basic problem lies in the fact that existing TCP sessions can be reset by sending specially crafted RST (reset) or Syn (synchronization) packets to either of the machines involved in the session. This is in fact an intended feature of the protocol. However, the source IP addresses on these packets can be forged, which makes it possible for attackers not involved in the TCP session to terminate the connection, causing a de facto denial of service.
News source: eWeek