Ramen, Slapper, Scalper and Mighty may sound like Santa's new team of reindeer, but they are creatures far lower down the evolutionary ladder -- and much less welcome. These are worms that have infiltrated Linux servers in recent months, commandeering the servers for use in distributed denial-of-service attacks. Linux enthusiasts who once believed they were less vulnerable to attack than Microsoft (Nasdaq: MSFT) users have begun to wonder whether they were overly optimistic.

But it is a mistake to think that one operating environment is inherently more risky than another, according to Eric Hemmendinger, research director at Aberdeen Group. The number of security flaws in software, he said, depends largely on the software's age.