The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Monday, May 13, 2019

They aren't attacking, they're being attacked

So that list of IP addresses I listed yesterday … it turns out they weren't the attackers, but the victims! And I was unwittingly helping to facilitate a DDoS amplification attack.


When we left off yesterday, I had modified my QOTD server to log the IP address, port number, and the incoming UDP packet to help figure out what the heck was going on. So pretty much off the bat, I'm seeing this (which goes on for nearly 4,000 entries):      "\001"      "\001"     "\001"      "\001"      "\001"     "\001"      "\001"      "\001"     "\001"

What had me puzzled are the ports—I wasn't familar with them. It may be that port 6951 deals with online transaction processing, port 7333 seems to have something to do with the Swiss Exchange, and nothing at all about port 37152. It's not exactly looking good, but the ports being attacked are rather all over the place (I'm only going to list two of the attacked IP addresses—there are more though):

Ports being attacked
host address port number requests
host address port number requests 10947 1508 11860 1425 14485 1420 65033 1418 4625 1409 4808 1401 37152 1400 65277 1394 27683 1389 17615 1389 48235 1388 27227 1386 14503 1386 43174 1385 43069 1377 47040 1372 6991 1370 18235 1369 57696 1360 7333 1233 6951 1204 36965 1171 16306 1139 47673 145 39606 144 48309 142 46769 142 59669 142 35763 142 22100 141 4302 140 53336 140 35758 138 44529 138 26878 138 52337 138

A lot of the ports are high values, which tend not to have defined services and are typically used for outbound requests to a service, like making a request to a QOTD service.

The data being sent is just a single byte, which is all that's really needed for the QOTD protocol to return a quote via UDP. So this looks like legitimate traffic, except for the volume.

But as I kept searching for “QOTD attacks” I kept coming across UDP amplification attacks (more of the same). It appears that the vast majority of traffic is forged (it's easy enough to forge UDP packets), and because QOTD sends more data than it receives, it's a rather cheap method to attack a target with a ton of traffic regardless of what the attacked machine is being used for (and my UDP based server probably isn't the only one unwittingly facilitating this attack).

A bit more research revealed a few servers that made a request (or a very small number of requests):

Requests to the UDP QOTD server
host address requests first request
host address requests first request 2 May 03 4 May 04 1 May 04 1 May 05 1 May 06 1 May 06 1 May 07 2 May 07 1 May 08 1 May 10 1 May 10

I'm guessing these machines made the query to see if my machine could be used for a UDP DDoS amplification attack, and would periodically check back to see if such attacks could continue from my server, which would explain the periodic nature of the deluge of traffic I saw (they weren't continuous but would happen in very random bursts). I also suspect there may be two different groups doing an attack, given the volume of traffic to certain targets.

It was also amusing to see attempt to spam me with email, and attempt to log in via ssh on the 7TH as well.

I've since disabled the UDP protocol on my QOTD server. Sigh. This is why we can't have nice things on the Intarwebs.

Obligatory Picture

[“I am NOT a number, I am … a Q-CODE!”]

Obligatory Contact Info

Obligatory Feeds

Obligatory Links

Obligatory Miscellaneous

You have my permission to link freely to any entry here. Go ahead, I won't bite. I promise.

The dates are the permanent links to that day's entries (or entry, if there is only one entry). The titles are the permanent links to that entry only. The format for the links are simple: Start with the base link for this site:, then add the date you are interested in, say 2000/08/01, so that would make the final URL:

You can also specify the entire month by leaving off the day portion. You can even select an arbitrary portion of time.

You may also note subtle shading of the links and that's intentional: the “closer” the link is (relative to the page) the “brighter” it appears. It's an experiment in using color shading to denote the distance a link is from here. If you don't notice it, don't worry; it's not all that important.

It is assumed that every brand name, slogan, corporate name, symbol, design element, et cetera mentioned in these pages is a protected and/or trademarked entity, the sole property of its owner(s), and acknowledgement of this status is implied.

Copyright © 1999-2024 by Sean Conner. All Rights Reserved.