Companies are taking too long to patch critical internal vulnerabilities and are still struggling to protect systems against external attacks.

That's according to Qualys CTO Gerhard Eschelbeck addressing the Black Hat conference in Las Vegas. He said that the typical patching time or "half life" for critical internal vulnerabilities was a concerning 62 days, about 22 days more than the 40 days he suggested companies should now be aiming for.

Eschelbeck also said that the time it took companies to patch against critical external vulnerabilities had improved in the last year from an average of 30 days to today’s figure of 21 days, about the level of decrease experts predicted. That still means that many companies are doing worse than this. Exploits for vulnerabilities are also being more rapidly deployed, cancelling out some of this gain.

The information was culled from 6.6 million anonymous real-world scans undertaken by the company since January 2002, 70 percent of which were carried out on Qualys customers with the remaining being random trials by visitors to its website. A total of 2,275 vulnerabilities classed as ‘critical’ were detected, defined as those which would allow intruders to take control of systems or result in information loss.

Not surprisingly given its market dominance, the top ten critical internal vulnerabilities named in Eschelbeck’s presentation all related to Microsoft software. The equivalent list of critical external vulnerabilities ranged across systems, but again problems with Microsoft products featured prominently.

The list of vulnerabilities has seen a 50 percent annual turnover rate, he said. “Some vulnerabilities occur again and again. They find new breeding grounds. Like human viruses, they find new victims,” said Eschelbeck referring to the way in which the same worms tended to recur.

“Vulnerabilities to web browsers, data centers, mail servers and other internal systems show up consistently in our top list of the most critical vulnerabilities. In most cases, worms are circulating faster than systems being patched inside the network, and organisations have to be more aggressive about protecting their internal systems.“

His advice was to assess which vulnerabilities were the most important. “Organisations don’t need to catch every vulnerability. They need to catch those which will affect them the most.”

A detailed summary of Eschelbeck’s Black Hat presentation can be found here.