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Re: isprime DOS in progress
From: David Andersen <dga () cs cmu edu>
Date: Sun, 25 Jan 2009 12:23:27 -0500

I'm not sure you're entirely out of the water yet:

17:13:45.680944 76.9.16.171.53868 > XXXXXXXX.53:  58451+ NS? . (17)
17:13:45.681251 XXXXXXXX.53 > 76.9.16.171.53868: 58451 Refused- 0/0/0 (17)

CIDR:       76.9.0.0/19
NetName:    ISPRIME-ARIN-3

In addition to the one that Brian Keefer mentioned a few days ago (206.71.158.30).

But on that subject, I figured I'd toss in a (sad) anecdote about security and upgrades. I'd upgraded this nameserver to bind-9 some time ago, during a bit of a security panic. And in the process, I screwed it up - I'd updated the machine itself, but had failed to propagate the changes to the master that sends updates to all of the servers. The obvious thing happened: after a while, this nameserver pulled its updates from the master, and downgraded to bind-8 again, which we didn't notice until I saw it spitting full cached NS responses to isprime hosts. Human error strikes again. Apologies for letting my host be an amplifier.

  -Dave


On Jan 23, 2009, at 1:11 PM, Phil Rosenthal wrote:

Just a friendly notice, the attack against 66.230.128.15/66.230.160.1 seems to have stopped for now.

-Phil
On Jan 22, 2009, at 6:01 AM, Bjørn Mork wrote:

Graeme Fowler <graeme () graemef net> writes:

I've been seeing a lot of noise from the latter two addresses after
switching on query logging (and finishing an application of Team Cymru's
excellent template) so I decided to DROP traffic from the addresses
(with source port != 53) at the hosts in question.

Well, blow me down if they didn't completely stop talking to me. Four
dropped packets each, and they've gone away.

Something smells "not quite right" here - if the traffic is spoofed, and
my "Refused" responses have been flying right back to the *real* IP
addresses, how are the spoofing hosts to know that I'm dropping the
traffic?

Did you filter *only* 66.230.128.15/66.230.160.1, or are you dropping
traffic from other sources too?  Looks like some of the other source
addresses are controlled by the DOSers. Possibly used to detect filters?

These clients may look similar to the DOS attack, but there are subtle
differences:

Jan 18 05:08:33 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:08:33 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:08:34 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:47:00 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 05:47:01 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 05:47:01 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 06:25:22 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 06:25:22 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 06:25:23 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 07:03:41 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:03:41 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:03:42 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:42:08 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 07:42:09 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 07:42:09 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 08:20:29 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:20:29 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:20:30 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:58:50 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 08:58:51 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 08:58:51 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 09:37:12 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied Jan 18 09:37:12 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied Jan 18 09:37:13 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied

Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied

Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:44:20 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 07:44:20 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 07:44:21 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:39:20 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied Jan 22 09:39:21 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied Jan 22 09:39:21 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied


Notice the pattern:
3 probes every 38 minutes
Each probe from the same source port
Source port increases slowly and steadily

This looks like some application actually waiting for a response. The slow source port change is probably an indication that this client only tests a small number of DNS servers. I guess that this client is either one of the many bots used to send the spoofed requests, or maybe a bot
not allowed to spoof its source and therefore used for other
purposes. In any case, I assume that other DNS servers may see such
control sessions coming from other addresses.

These 3 clients started probing my DNS server almost simultaneously on January 8th:


Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:36:29 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:36:29 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:36:30 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied

Maybe preparing for the attack on ISPrime?  I didn't start receiving
spoofed requests from 66.230.128.15/66.230.160.1 before January 20th


I just tried filtering the probing addresses.  This made the probing
stop immediately after dropping a set of 3 probes.  But the spoofed
requests continuted at the same rate as before, so this does not support
my theory.

However, I believe it would be too much of a coincidence if there isn't
some connection between the probing and the DOS attack.  It would be
interesting to hear if others see similar probing.



Bjørn





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