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Date:      Sun, 5 Aug 2001 13:31:38 -0500
From:      Mike Meyer <mwm@mired.org>
To:        Kent Stewart <kstewart@urx.com>
Cc:        Louis LeBlanc <leblanc+freebsd@acadia.ne.mediaone.net>, questions@freebsd.org
Subject:   Re: Attempted Buffer Overrun in via httpd?
Message-ID:  <15213.37130.443656.153817@guru.mired.org>
In-Reply-To: <3B6D8955.7B346069@urx.com>
References:  <15213.29533.375904.18788@guru.mired.org> <3B6D8955.7B346069@urx.com>

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Kent Stewart <kstewart@urx.com> types:
> Mike Meyer wrote:
> > What scares me is the possibilitity of near-exponential growth of the
> > thing. I've put up a plot of hits/hour since it started - at about 9am
> > CDT - to now at <URL: http://www.mired.org/codered.ps >. Discount the
> > last data point - it only includes about 15 minutes of hits. The large
> > jump around 9am 8/4 got me, but it seems to have peaked at 45/hour,
> > and fallen back to ~15/hour. I can understand the levelling out as the
> > population of suspect servers approaches saturation, but why is did it
> > drop off? Or is the spike just random noise?
> Your hit rate is much greater than mine. My complete list of error log
> messages are on http://dsl1-160.dynacom.net/code_red.html. The complete
> list is only 4 screens of text.

That's strange. More commentary on this later.

> I am also seeing a mutation. The first error log message was the typical
> one but yesterday, the second one also started showing up.

There are at least two versions of this worm running around. One
defaces the web pages, one doesn't. There are also differences in the
random number generators used, the earlier ones using the same PRNG
and seed, meaning they'll probe the same list of IP addresses.

> [Sun Aug 5 08:31:26 2001] [error] [client 212.205.80.11] \
> Client sent malformed Host header
> [Sun Aug 5 08:41:47 2001] [error] [client 24.2.244.206] \
> File does not exist: /usr/local/www/data/default.ida

I hadn't been counting the first one - it's not mentioned in any of
the writeups I saw. I've also got some during the period when code red
is supposedly quiescent. While those are likely to be infected hosts
with misset clocks, I'm going to leave it as is because 1) I'm more
interested in trends than in total numbers, and 2) the totals seem to
be at most 4/hour, meaning they are for the most part lost in the
noise.

One possible explanation for the discrepancy we're seeing in counts is
that you somehow overlooked the initial ones that didn't have a
malformed host header. Another is that those without a malformed host
header are the older worm, and I'm much lower on that fixed list of IP
addresses than you are. That doesn't seem likely, as I didn't see any
of those until August.

	<mike
--
Mike Meyer <mwm@mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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