Vulnerability Assessment & Network Security Forums

If through a vulnerability assessment, a network security issue is detected for the vulnerability below, applying the appropriate security patches in a timely matter is very important. If you have detected that your system has already been compromised, following CERT's Network Security recovery document will assist with recommended steps for system recovery.

Home >> Browse Vulnerability Assessment Database >> Useless services >> Chargen

Vulnerability Assessment Details

Chargen

Vulnerability Assessment Summary
Searches for the existence of chargen

Detailed Explanation for this Vulnerability Assessment

Summary :

The remote host is running a 'chargen' service.

Description :

When contacted, chargen responds with some random characters (something
like all the characters in the alphabet in a row). When contacted via UDP, it
will respond with a single UDP packet. When contacted via TCP, it will
continue spewing characters until the client closes the connection.

The purpose of this service was to mostly to test the TCP/IP protocol
by itself, to make sure that all the packets were arriving at their
destination unaltered. It is unused these days, so it is suggested
you disable it, as a possible hacker may use it to set up an attack against
this host, or against a third party host using this host as a relay.

An easy attack is 'ping-pong' in which a possible hacker spoofs a packet between
two machines running chargen. This will cause them to spew characters at
each other, slowing the machines down and saturating the network.

Solution :

- Under Unix systems, comment out the 'chargen' line in /etc/inetd.conf
and restart the inetd process

- Under Windows systems, set the following registry keys to 0 :
HKLM\System\CurrentControlSet\Services\SimpTCP\Parameters\EnableTcpChargen
HKLM\System\CurrentControlSet\Services\SimpTCP\Parameters\EnableUdpChargen

Then launch cmd.exe and type :

net stop simptcp
net start simptcp

To restart the service.

Network Security Threat Level:

Low / CVSS Base Score : 2
(AV:R/AC:L/Au:NR/C:N/A:P/I:N/B:N)

Networks Security ID:

Vulnerability Assessment Copyright: This script is Copyright (C) 1999 Mathieu Perrin

Cables, Connectors