While email worms and viruses capture the most media attention, another threat to enterprise networks quietly looms as a growing menace: <A HREF="http://searchdomino.techtarget.com/originalContent/0,289142,sid4_gci1031410,00.html">viruses transmitted via instant messaging.</A> As the popularity of instant messaging within the enterprise grows, so does the potential for security threats to organizations that depend on such messaging to communicate.