RE: [iwar] ATT@Home cable enumeration attack

From: Robert D. Hughes (rob@robhughes.com)
Date: 2001-11-20 17:27:52


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Thread-Topic: [iwar] ATT@Home cable enumeration attack
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From: "Robert D. Hughes" <rob@robhughes.com>
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Date: Tue, 20 Nov 2001 19:27:52 -0600
Reply-To: iwar@yahoogroups.com
Subject: RE: [iwar] ATT@Home cable enumeration attack
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Well, no, not really. The way @Home configures IPs, or at least the
way many of the MSOs do it, is to configure a static DHCP lease on
their servers. So, if a host was configured, then the subscriber
terminated service, the in-addr and host name records would still be
configured, but there wouldn't be a host there. The same is true if
they just turned off their system.

- -----Original Message-----
From: Fred Cohen [mailto:fc@all.net]
Sent: Thursday, November 15, 2001 7:21 PM
To: Information Warfare Mailing List
Subject: [iwar] ATT@Home cable enumeration attack


AT&T/@Home has standardized on using DHCP for end-user workstation
configuration. This configuration is done via the standard DHCP 
implementation, but also is configured to send a string to the
DHCP server with the "hostname" of the client.

This hostname is adminstratively defined by AT&T and is a unique
customer number. An example is...

 cb666699-a.anytwn.il.home.com

Where the customer ID is cb666699-a in the subdomain of anytwn.il

What frightens me is that no PTR records are configured except for
this
dynamic method. By scanning for PTR records, it is easy to determine
active IP addresses and focus attack efforts on those IPs only,
speeding
up possible intrustions (imagine how much quicker it is if only
20,000 hosts are listening on a 24/8 subnet!)

This implementation, while not a true "vulnerability", is not quite a
"Best Practice".

- -#0

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