Nachi/Welchia Aftermath

[Brent Van Dussen <vandusb () attens com>]

Well folks, since the middle of August I've been tracking the spread and 
subsequent efforts by our community to stop the nachia/welchia infection 
that took down so many networks.

Sadly, by my estimations, only about 20-30% of infected hosts were 
cleaned.  After Jan 1, 2004 it appears that the thousands, (millions?) of 
remaining infected hosts were rebooted and the worm removed 
itself.  Network traffic has finally returned to normal.

What kind of effects did everyone see from this devastating worm and what 
lessons did we learn for preventing network downtime in the future?