News 

Kaminsky, the security researcher who first unveiled the security flaw earlier this month, explained that 86% of computers were vulnerable on the day of release, but that just over half had still to protect against the problem by installing software updates.

"Not perfect; not even good enough," says Kaminsky, speaking in a webinar prior to the Black Hat security conference, although he would "take 52 any day of week and twice on Sunday."

Kaminsky discovered the flaw six months before its release, but had kept details quiet while an unprecedented effort involving Microsoft, Sun and Cisco was underway to develop fixes.

The flaw affects the DNS system, which translates web addresses into IP addresses. The flaw can poison DNS records so that users will be redirected to malicious websites, even if they typed the correct address of a legitimate website.

Previous attacks on DNS servers have been documented before, but Kaminsky's approach can speed up attacks and is therefore far more potent.