CHARGEN - is a service of the Internet Protocol Suite defined in RFC 864 in 1983 by Jon Postel. It is intended for testing, debugging, and measurement purposes. The protocol is rarely used, as its design flaws allow ready misuse.
Impact of running CHARGEN devices
Since CHARGEN runs over UDP, again, it can be used for UDP reflection attacks. Details CHARGEN's amplification factor is ~360 times, making it one of the more effectively abuseable protocols for UDP amplification.