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Vulnerability Assessment Details
Detailed Explanation for this Vulnerability Assessment
Florian Lohoff discovered a bug in the dhcrelay causing it to send a
continuing packet storm towards the configured DHCP server(s) in case
of a malicious BOOTP packet, such as sent from buggy Cisco switches.
When the dhcp-relay receives a BOOTP request it forwards the request
to the DHCP server using the broadcast MAC address ff:ff:ff:ff:ff:ff
which causes the network interface to reflect the packet back into the
socket. To prevent loops the dhcrelay checks whether the
relay-address is its own, in which case the packet would be dropped.
In combination with a missing upper boundary for the hop counter an
attacker can force the dhcp-relay to send a continuing packet storm
towards the configured dhcp server(s).
This patch introduces a new command line switch -c maxcount and
people are advised to start the dhcp-relay with dhcrelay -c 10
or a smaller number, which will only create that many packets.
The dhcrelay program from the "dhcp" package does not seem to be
affected since DHCP packets are dropped if they were apparently
For the stable distribution (woody) this problem has been fixed in
The old stable distribution (potato) does not contain dhcp3 packages.
For the unstable distribution (sid) this problem has been fixed in
We recommend that you upgrade your dhcp3 package when you are using
the dhcrelay server.
Solution : http://www.debian.org/security/2003/dsa-245
Network Security Threat Level: High
Networks Security ID: 6628
Vulnerability Assessment Copyright: This script is (C) 2005 Michel Arboi
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