Re: Blaster: will it spread without tftp?

[Russell Fulton <r.fulton () auckland ac nz>]

On Wed, 2003-08-13 at 14:13, Nick FitzGerald wrote:
> "Maarten" <subscriptions () hartsuijker com> wrote:
>
> > I was wondering about the following scenario:
> <<snip>>
> > - since these other vulnerable systems are using a proxy server to connect
> > to the internet and a firewall prevents all other connections, tftp servers
> > on the Internet can not be accessed
>
> Good up to here, but then...
>
> > - since tftp servers can not be accessed, msblaster.exe can not be
> > downloaded
>
> No.
>
> When the worm connects from its current victim to a new, vulnerable 
> host it tells the new victim to TFTP the worm's .EXE from the current 
> victim machine where the worm briefly sets up a TFTP thread to serve 
> its .EXE.

I can confirm this.  We block tftp at the gateway (as well as all the MS
ports 135-139, 445 etc.).  An infected laptop was brought on to the
internal network and half an hour later we had 500 infected systems and
a very soggy network.

Note, that those 500 was out of a total of 7500, we had managed to get
the rest patched, another week and we would have only had a handful. 
Yes we are now investigating how we can speed up patch deployment ;-)

-- 
Russell Fulton, Network Security Officer, The University of Auckland,
New Zealand.

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