mailing list archives
Internet Wide DOS Attack using IRC
From: dbarba () GEOCITIES COM (dbarba)
Date: Fri, 2 Oct 1998 14:38:04 -0700
Please forward this on to the appropriate people if necessary.
GeoCities is currently experiencing a DOS attack that appears to be
spread by a trojan horse in a mIRC script.
GeoCities is receiving thousands of HTTP requests from thousands of
unique computers daily for a file that no longer exists on our
The specific count for one minute on Friday, September 25 at 10:17 am
was 3,522 hits,
1,492 of them were from unique IP's. For the time period of 3 am to
on 9/25 we had 3,562 unique IPs request this one file. It does not
appear to be
specifically requested by the user of that computer. This request
no browser and is usually requesting the file every 30 seconds while
user is connected to the Internet. The requests are coming from
the world and have been slowly building up since at least August 18,
1998 (the farthest back our access logs go).
The attack is requesting a file from our site:
The complete content of the 5845 directory was: nfo.zip, nfo.jpg,
servers.zip, servers.jpg, users.zip and users.jpg. When I looked at
binary files by doing a cat, the users jpg & zip files were the
same, but the
other files were all unique.
It does not use a browser or store cookies. At the moment, the file
requested is of zero size. When there is a file of size , originally
it was 8k
and I later inserted a short note to contact me regarding the attack
nfo.zip file, at which time the attack becomes much worse on the
machines that are requesting the file.
Also, an odd note, there are a couple machines that are requesting
the file named
nfo.jpg. Those are reqeusted every minute instead of every 30
I have contacted a user that complained about GeoCities attacking
In reality, his computer was asking for the nfo.zip file from us
30 seconds, and that was flooding his connection to the internet. I
have worked with him closely since he found the problem. He only
IRC. In fact, the first time he visited our website is after the
started, when he was looking for a contact name and number. He does
surf the internet. He has subsequently reinstalled his OS and that
completely stopped the attack.
We did find an entry in his registry with the following setting:
a) " "
When the user deleted the registry entry, the attack from his
went from 1 GET every 30 seconds to 1 GET every second. After about
minutes, it started slowing up and finally settled into about 1 GET
every 17-20 seconds.
I also asked our ISP to help track some of this and this was their
result. "All the IP's
I've scanned so far from the log have several UDP ports open in the
(what Back Orifice uses)."
So, we really need to find the source instead of asking everyone to
reinstall their OS. It might also be necessary to inform the various
virus-detection software vendors to try to eradicate this from all of
the machines that currently have it installed.
Thank you for your help,
dbarba () geocities com