Intruders can disrupt the normal operation of a 3Com HomeConnect Cable Modem.
The 3Com HomeConnect Cable Modem contains a web server. This web server is used to administer the cable modem. By default, this web server is configured to allow any user (local or remote) to connect to 80/tcp.
If an intruder connects to the web server and issues a specially crafted GET request, the cable modem will reset. When the modem resets, it will lose all of it's network configuration information along with any other configuration data. Until this data is restored, the hosts on the internal side of the cable modem will have no connectivity to the outside network.
The CERT/CC is currently unaware of a practical solution to this problem.
Configure the cable modem to filter 80/tcp.
Vendor| Status| Date Notified| Date Updated
3Com| | -| 27 Dec 2001
If you are a vendor and your product is affected, let us know.
Group | Score | Vector
Base | N/A | N/A
Temporal | N/A | N/A
Environmental | N/A | N/A
The CERT/CC thanks Alex S. Harasic for reporting this vulnerability.
This document was written by Ian A. Finlay.