Could this be related to a recent Bugtraq posting by Paul Starzetz? Read below: > Hi ppl, > It is time for a new ´nuke´ - ARPNuke. > There is an ARP table handling bug in Microsoft Windows protocoll > stacks. It seems that the arp handling code uses some inefficient data > structure (maybe a simple linear table?) to manage the ARP entries. > Sending a huge amount of ´random´ (that is random source IP and > arbitrary MAC) ARP packets results in 100% CPU utilization and a machine > lock up. The machine wakes up after the packets stream has been stopped. > > The needed traffic is not really high: the attached ARPkill code will > send an initial sequence of about 10000 ARP packets, then go to ´burst > mode´ sending definable short burst of random ARP packets every 10 msec. > The lockup occured at about 80kb/sec (seq about 45) on a PII/350. > > Even worse: it seems that is possible to kill a whole subnet using > broadcast destination MAC (that is ff:ff:ff:ff:ff:ff) and arbitrary > source IP. > > > regards, > > Ihq. Hoyt Plunkett Development Technologist Matmon Internet, Inc. (501) 375-4999 ################################################### PGP Public Key: http://www.phrenic.org/pgpkey.txt ################################################### -----Original Message----- From: Mike Brown [mailto:mikebrownat_private] 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 ---------------------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
This archive was generated by hypermail 2b30 : Wed Aug 08 2001 - 11:13:05 PDT