These packets contained the return address of the intended victim. The flood of PING requests caused the site to issue a flood of responses, the volume of which could cause both the target and the intermediary site to crash. A similar attack was the Fraggle attack, which used UDP echo packets to accomplish the same goal. Perhaps the most exploited system vulnerability is the buffer overflow. Unfortunately, many systems fail to check the characteristics of arguments being passed between systems and applications.
Systems accept input of any length, place the overflow on the stack and attempt execution.
With a properly configured string, attackers can even gain root access. Denial of service. One of the most infamous of these attacks is the SYN flood, in which a flood of requests to establish a connection leave the target system with more open connections than it can support. As a result, the system denies all legitimate requests for connection until the open request can time out. In these recent and much heralded attacks, intermediary systems are compromised and used to launch an attack against other systems.