Microsoft Updates Triggered Skype Service Outage

Voice over IP service provider Skype on Monday said the two-day outage it suffered last week was the result of a large number of users attempting to reconnect to the service after downloading Microsoft's monthly patch updates.

In a blog entry, Skype spokesperson Villu Arak noted that the large number of restarts, followed by users trying to log back into the Skype service, triggered a domino effect that taxed network resources and uncovered a glitch in the company's backend infrastructure.

"Normally Skype's peer-to-peer network has an inbuilt ability to self-heal, however, this event revealed a previously unseen software bug within the network resource allocation algorithm which prevented the self-healing function from working quickly," wrote Arak.

Rumors swirled last week that the outage was the work of Russian hackers after an anonymous poster claimed to have discovered a buffer overflow exploit in the Skype authorization server. However, Arak dismissed this possibility.

"We can confirm categorically that no malicious activities were attributed or that our users' security was not, at any point, at risk," wrote Arak.

Denial of service situations are often caused not by hackers, but by poorly designed networks and infrastructure that's unable to handle heavy traffic, according to Babak Pasdar, founder and CTO of igxglobal, Clifton, N.J..

Pasdar says the situation that befell Skype can also occur in organizations that use virtual private networks. For example, when Internet service goes down and then comes back up, and all the users' VPN tunnels attempt to re-connect at the same time.

"You end up 'denial of servicing' yourself because of all the preliminary checks the system requires, and a lot of organizations don't account for that," Pasdar said.