A vulnerability in the Internet Software Consortium's "dhcrelay" makes it possible for a remote attacker to use dhcrelay to launch a denial-of-service attack against a victim dhcp server.
The Internet Software Consortium (ISC) produces a "freely redistributable reference implementation of all aspects of the DHCP protocol, through a suite of tools." One of these tools is a dhcp relay agent (dhcrelay). From the dhcrelay man page:
The Internet Software Consortium DHCP Relay Agent, dhcrelay, provides a means for relaying DHCP and BOOTP requests from a subnet to which no DHCP server is directly connected to one or more DHCP servers on other subnets. The DHCP Relay Agent listens for DHCP and BOOTP queries and responses. When a query is received from a client, dhcrelay forwards it to the list of DHCP servers specified on the command line. When a reply is received from a server, it is broadcast or unicast (according to the relay agent's ability or the client's request) on the network from which the original request came.
A remote attacker can use dhcrelay to launch a denial-of-service attack against DHCP servers configured to communicate with the dhcrelay host.
Apply a patch from your vendor.
Internet Software Consortium
Red Hat Inc.
Apple Computer Inc.
Cisco Systems Inc.
This vulnerability was discovered by Florian Lohoff and reported to the BugTraq mailing list on January 15, 2003.
This document was written by Ian A Finlay.
|Date First Published:||2003-02-04|
|Date Last Updated:||2003-05-30 16:44 UTC|