|Summary:||Checks for the presence of chargen|
The remote host is running a 'chargen' service.
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 an attacker 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 an attacker 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.
- 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 :
Then launch cmd.exe and type :
net stop simptcp
net start simptcp
To restart the service.
Common Vulnerability Exposure (CVE) ID: CVE-1999-0103|
Cert/CC Advisory: CA-96.01.UDP_service_denial
XForce ISS Database: echo
XForce ISS Database: chargen
XForce ISS Database: chargen-patch
|Copyright||This script is Copyright (C) 1999 Mathieu Perrin|
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