There's been a 65% increase in network vulnerabilities in the third quarter of this year compared to the same time last year, according to a new study from Internet Security Systems, Inc.

The study also shows that the growth of hybrid threats has increased nearly 30%, while the number of new vulnerabilities has grown at a rate of nearly 9% since the first quarter of this year.

"One area we are watching closely is the aggressive nature of recent worms, which are both persistent and increasingly sophisticated in their ability to evade traditional network perimeters and antivirus defenses," says Chris Rouland, a director at Internet Security Systems (ISS), an Atlanta-based security firm.

Actually, the ratio of new hybrid threats to new vulnerabilities increased for each quarter -- going from 21% in the first quarter to 25% in the third quarter.

Worms are actually increasing, not only in capability, but also in time to delivery, according to Dan Ingevaldson, a team leader at ISS.

"One of the things we've seen over the last quarter is that when worms are coming out there's an ever-decreasing amount of time between the initial release of the vulnerability and the time when it's rolled into a worm and released," says Ingevaldson. "Nimda used a vulnerability in Internet Information Services (IIS) that was a year old. The Slapper worm came out about two weeks after the announcement of the Apache vulnerability."

Ingevaldson says that means it's more important than ever to stay on top of needed patches and to stay aware of what vulnerabilities are cropping up. But he says it's just as important not to rush blindly into installing anything -- even a patch.

"It's not just about downloading a patch and installing it," he explains. "There's an enormous cost to it. You've got to do testing. Does security have the right to apply patches to servers run by IT? What if the patch breaks the system? It shouldn't be a knee-jerk reaction."

Ingevaldson also points out the survey shows that on average 21% of security events happen over the weekend, when the security staff is generally at its lowest level. But Tuesdays show the highest rate of security events throughout the third quarter, logging in at 297,379.