Potentially the most crippling malware thus far conceived, the Conficker worm has infected 10 million PCs to date. Each PC polls 250 random domains each day in search of a malware payload that has yet to appear. Should a payload be released to one of the domains, the PCs will download and install the package to create the biggest bot or spam net in history. OpenDNS and Kaspersky hope to stem the tide before it forms.

The OpenDNS service is using a growing list of domains that security firm Kaspersky has developed after reverse engineering the worm. Administrators running OpenDNS on their network will be alerted to infected PCs and partially protected against infected clients connecting to one of the domains that may contain a payload.

The service will also help network admins to quickly pinpoint any infected machines by checking their OpenDNS Dashboard. Starting Monday, any networks with PCs that try to connect to the Conficker addresses will be flagged on an admin’s private statistics page. The service is available for free to both businesses and home users.

“The idea of blocking things on the network and doing it for consumers is a big change,” said OpenDNS CTO David Ulevitch. “Overall, we think we’re uniquely positioned to do this.”

Let’s hope that preventative maintenance can make a difference, because Conficker could have devastating consequences if activated.