[Full-Disclosure] Comcast using IPS to protect the Internet f rom their home user clients?
Tom.Chmielarski at motorola.com
Wed Mar 10 13:46:09 GMT 2004
Yes, they say they are now doing this.
From: full-disclosure-admin at lists.netsys.com [mailto:full-disclosure-admin at lists.netsys.com] On Behalf Of Frank Knobbe
Sent: Monday, March 08, 2004 8:29 PM
To: full-disclosure at lists.netsys.com
Subject: [Full-Disclosure] Comcast using IPS to protect the Internet from their home user clients?
This post should probably have gone to SF-PenTests, but since it is more of a discussion item, I thought about Full Disclosure, the list for vuln info and everything else :)
Anyhow, I noticed that certain vulnerability scans, for example scans using Nikto and similar tools, when run from a Comcast address show a different behavior than when they are run from a clear, uncontrolled Internet connection (i.e. corporate T-3). In fact, it appears like Comcast has an Inline-IDS (some call it an IPS ;) sitting on its wires, filtering out certain signatures and blocking subsequent access for a short period of time. For example, scan progresses, then hangs inexplicably, then resumes, trips a sig, and hangs again. At the same time, the same scan from a non-Comcast address continues without any hick-ups. Targets have been ruled out (up and running, verified at the same time from different addresses), and connectivity to the rest of the net remains. It's looks like just the src-dst address pair is used so that all connections from a Comcast src to that particular dst are blocked for a short moment (1-5 minutes).
Has anyone else noticed that? Is Comcast actually attempting to keep all those worms'n'viruses of their clients away from the Internet?
How many other ISP's are known to use IPS's inline to protect themselves from the 'Net, or protect the 'Net from themselves?
Frank (routing all scans via VPN through corporate hosts ;)
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