RE: Using a Stand-Alone Network Printer as a network attack entry point?

From: Brewis, Mark (mark.brewis@eds.com)
Date: Fri Aug 16 2002 - 13:36:04 EDT


Nick,

Not such a stupid idea - we have come up with several scenarios in the past
using printers to compromise networks, but only once inside a network.

Many printers are crammed full of functionality, something I've alluded to
in previous posts (not necessarily to this list.) Web server management
interfaces and ftp servers are common, and some file server functionality
isn't uncommon.

One printer manufacturer provided proxy functionality from the printer to
another web server, to facilitate central management and configuration of an
enterprise print environment. We guessed the (trivial) admin password,
grabbed the web pages off the printer, and configured the printer to use a
host of our choice as proxy. We didn't have time to take the scenario any
further, but there were several interesting possibilities, including some
custom JavaScript with teeth.

>>The idea here would be to take a SNP and modify a ROM image for the
specific printer to include the proxy functionality. I
realize this could turn out to be quite difficult,<<

Difficult to do at the technical level - a lot of the printer code is really
odd, based on custom OS and file systems. But someone wrote it, so someone
else can write a hacked up version.

>>but at the same time, it would provide a way into the internal network
when no others are available.<<

Are you looking at this as an internal exploit, or trying to trojan printers
before installation? I could see it working in the first instance, but it
being a potentially intractable problem in the second instance.

Mark

Mark Brewis

Security Consultant
EDS
Information Assurance Group
Wavendon Tower
Milton Keynes
Buckinghamshire
MK17 8LX.

Tel: +44 (0)1908 28 4234/4013
Fax: +44 (0)1908 28 4393
E@: mark.brewis@eds.com
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