[Mimedefang] netsky.c passing MD-2.40 with clamav+uvscan

[Alan Lehman]

I'm seeing a fair number of netsky.c infected zip files pass my system 
(MD-2.40) with clamav and uvscan configured. Most are caught by MD, but 
  the misses are being caught at a downstream eggchange box running 
Mcafee groupshield. The default filter section "look inside zip files" 
is enabled. I tried blocking specific zip file names. That helped, but 
new ones kept showing up, so I gave up and started blocking all zip 
files today. That stopped the occurances at the exchange box. Any ideas?

It seems curious that groupshield catches stuff that gets past uvscan.

Also, since I started blocking zip files, I'm still seeing 
W32/Netsky.c at MM!zip viruses being reported by MD. Does it scan for 
viruses in files that are rejected based on filename extension?

thanks,
Alan