McAfee users had their internet access severed and were left exposed to malware after the company issued an anti-virus update containing glitches.

The update affected all Windows McAfee suites and VirusScan products, including the latest version of VirusScan Enterprise and McAfee SecurityCenter, after anti-virus signature updates (DAT 6807, 6808) disabled the anti-virus clients and in some cases, severed internet access.

McAfee issued an enterprise 100Mb Super DAT (Hotfix 793640) and a consumer fix (DAT 6809) overnight for the faulty updates, which it rated as ‘critical'.

Enterprise customers had to apply the hotfix as a product update through the e-Policy Orchestrator, while consumers were advised to remove McAfee anti-virus from affected machines and re-install the product in order for the fix to be applied.

Furious enterprise and business customers posted comments yesterday on the McAfee blog claiming they were left high and dry after thousands of machines within their companies were left exposed by the updates.

One user had 70 of more than 2,000 systems affected, including two ‘high-profile' users. Some consumers took to McAfee's Facebook page, where support officers were assisting with technical support, to vent their anger.

McAfee said that it appreciated the seriousness of the situation, apologised for the inconvenience and said that the development teams were working to get a solution ready as fast as possible. It later offered guidance to solve the problem and recommended users who had not deployed DAT 6807 or 6808 to go directly to DAT 6809 or later.

A McAfee statement said: “Over the weekend, McAfee issued an update that caused disruption of internet service and functionality issues for some customers. We have updated the file and are working very closely with the affected customers to update their product and restore internet service.

“For our business customers, we have issued a mandatory security hotfix to ensure the ongoing efficacy of their security systems. The hotfix is available on the McAfee knowledgebase site at https://kc.mcafee.com/corporate/index?page=content&id=KB76004.”