We set up botnet filtering yesteray. We have about 300 users behind the ASA-5510. What a great tool! But, the filter claims that we have about 70 "infected machines".
I investigated some of the IPs, like 188.8.131.52. That IP belongs to Google and if you try http on that IP you get their search engine. And every hit that we got was said to be "very high risk". Many of the IPs that are in the database appear to innoculous. So I'm wondering what's going on.
Also, we use DNS substitution. When I enable DNS snooping, the substitution doesn't work, the query returns th outside IP. I hava a SR open on this.
We did a bit of sniffing and found tha the "infected" hosts we not actually infected, Most often the user was visiting a compromised ecommerse site (usually built with an outdated version of Wordpress) and these site were redirecting to a malware site. So the cases that we looked at, the user was not infected (yet)
It is dropping about 1000 connections across 40 PCs per day.
We have enabled automatic blacklisting and have not yet had any complaints.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...