Vulnerability Note VU#568073

Canon digital multifunction copiers FTP bounce vulnerability

The FTP Bounce Attack

To conform with the FTP protocol, the PORT command has the originating machine specify an arbitrary destination machine and port for the data connection. However, this behavior also means that an attacker can open a connection to a port of the attacker's choosing on a machine that may not be the originating client.

The following workarounds may mitigate this vulnerability:

Disable the affected FTP server
Administrators and users should either turn off the vulnerable FTP server or disable anonymous access. For more information, see the "Steps to take to clear vulnerability" section of the Canon Web Advisory: Digital multifunction printer vulnerability.

Use host-based firewalls
Administrators and users can use host-based firewalls to prevent affected printers and other devices from creating connections to arbitrary TCP ports.

Systems Affected

http://www.usa.canon.com/html/security/pdf/CVA-001.pdf
http://www.canon-europe.com/For_work/Canon_Europe_CBS_Web_Advisory_Digital_Multifunction_Printers.asp
http://www.cert.org/tech_tips/ftp_port_attacks.html#3.2
http://nmap.org/hobbit.ftpbounce.txt

Credit

Thanks to Canon for information that was used in this report. Canon credits Nate Johnson and the Indiana University for reporting this vulnerability.

This document was written by Ryan Giobbi.

Other Information

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