full-disclosure - RE: Probable new MS DCOM RPC worm for Windows

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From: derek at cynicism.com (Derek Vadala)
Subject: RE: Probable new MS DCOM RPC worm for Windows

> I'm thinking that there *has* to be a variant of Nachi/Welchia in the
> wild.  We have machines that were patched for MS03-026 (verified by
> scanning with multiple scanners) but not patched for MS03-039 (ditto)
> and they have been infected by something that triggers my Nachi rule in
> snort.  This should *not* be possible with the "original" Nachi/Welchia,
> so my assumption is that either something new has been released or the
> worm has mutated somehow.
>
> Mind you, this is anecdotal and a very small incidence (only three
> machines so far), but it still bears watching IMHO.  I've been surprised
> to not see any discussion on the lists about a new variant.  Perhaps no
> one is looking?
>
> Paul Schmehl (pauls@...allas.edu)

We've seen the same thing over here. I've had a handful of machines
(perhaps 15-20 out of 2500) here that were reported to be patched against
MS03-026 yet became infected with Welchia. These machines were not patched
against MS03-039. One possibility is that the systems were already
infected with Welchia at the time they were patched against MS03-026.

I know of at least one or two cases here where the technical support
person assigned to fix a particular system didn't appropriately follow the
removal procedures and left a patched, but infected, system. I have to
assume this is happening without notice in other cases, since there
haven't been reports of a variant, and the number of systems in this
situation is rather low.

So I'm betting user error, though I find it hard to believe there isn't
another variant making the rounds.