Integrated message management firm Postini has revealed that its systems registered a 500 per cent increase in instant messaging attacks during May, demonstrating that hackers are seizing the opportunity in compromising IM networks.

Postini recorded numerous IM viruses and worms, such as Browaf, Tilebot and Khoobe, which attempt to infiltrate customer networks.

The statistics underscore the need for businesses to secure IM networks from unwanted traffic, according to Postini, which reported that corporate IM traffic increased 138 per cent in May.

"The fact that instant messages more than doubled in just one month shows the rate at which companies are adopting IM as a mainstream business communications tool," said Andrew Lochart, senior director of marketing at Postini.

"The sheer volume of IM attacks is a dramatic demonstration that hackers, knowing that most organisations are still unprotected against IM malware, are rapidly adopting IM for their attacks.

"That said, IM attacks are still only a fraction of the number of email attacks, so it's important that companies keep up their guard on both fronts."

Postini processed more than 25 billion email messages in May, a 13 per cent increase from April, reporting that more than 86 per cent of all traffic contained malicious or unwanted content.

The top five viruses reported by Postini for May were MyTob variants, followed by Netsky, Swen, Mydoom and LovGate.