Security Incidents mailing list archives
RE: Code Red, ARP and YOU!!
From: Chad Loder <cloder () acm org>
Date: Wed, 08 Aug 2001 14:05:58 -0700
The ARPs are getting sent out directly from your router(s), which is why you see them coming from only those one or two IP addresses. It's a result of Code Red II (or III or whatever the hell they decided to call it) hitting lots of non-existent addresses on your subnet. Each time you try to hit a non-existent address, it causes the router to ARP out and say "Hey, anyone have this address?" I posted something about this to incidents () securityfocus com over the weekend, so you might want to check the archives. I'd give you the exact URL but the securityfocus.com website seems to be down temporarily. The title of the email was "Code Red III - increased ARPing on shared segment broadband" Cheers, Chad Loder Rapid 7, Inc. http://www.rapid7.com At Wednesday 8/8/2001 12:28 PM -0500, you wrote:
-----Original Message----- From: Mike Brown [mailto:mikebrown () cfl rr com] Sent: Sunday, August 05, 2001 11:29 PM Cc: recipient list not shown: ; Subject: Code Red, ARP and YOU!! This may be obvious to many, but it stumped me for 5 or 10 mins, so allow me to share. Today after I got home from work I looked at my cable modem and it's data light was blinking like there was no tomorrow. My first thought, OMG I finally got hacked! And I'm part of a DDoS attack, Wohoo for me! "About time" I thought, now the fun part. How did they do it? Well sadly it wasn't to be. After Much looking I found that no programs where running that shouldn't and that there where no connection that didn't belong. So I fired up Ethereal and had it listen for 17 seconds. In those 17 seconds I recorded 474 packets coming and going from my pc. The fun part is 451 of them are ARP broadcasts. And all of them are coming from just 2 IP's. My theory is that because on a cable modem network no one ever needs to contact any other host besides the router none of the hosts know the other IP's thus the flood of ARP requests. Now the useful part. There was some talk about the moral implications of scanning others servers, especially from the ISP's side. They don't want to piss anyone off but they don't want to host the worm of the day. Well the really passive way to detect the Code Red worm of any version is to look for the exponential growth in ARP traffic on your network. Now on my network the two offending IP's are 65.33.140.1 and 24.27.216.1 judging from the last octet they could be routers but the basic idea holds true, just look on the other side of the routers. Now if I've missed something incredibly obvious (besides my spelling and mind) please pardon me, Mike the lowly Tier one tech support guy. But I think I've got something here. Is there any other reason to see dozens of ARP requests a second coming from the same host? - Mike
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Current thread:
- RE: Code Red, ARP and YOU!! Hoyt Plunkett (Aug 08)
- RE: Code Red, ARP and YOU!! Chad Loder (Aug 09)