dhcp3 - ignored counter boundary
| Package(s): | dhcp3 | CVE #(s): | CAN-2003-0039 | ||||||||||||||||
| Created: | January 28, 2003 | Updated: | April 5, 2003 | ||||||||||||||||
| Description: | 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 commandline 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 relayed already. | ||||||||||||||||||
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