Virus-infected computers should be blocked from the internet and kept in quarantine until they are given a “health certificate”, a top Microsoft security researcher suggested on Thursday.

Under the proposed security regime, put forward by the technology giant’s trustworthy computing team, an individual’s internet connection would be “throttled” to prevent the virus spreading to other computers. But security experts today warned that cutting people off from the internet could be a drastic step too far – and that the question of who would issue and verify the “health certificate” was troubling.

Millions of computers around the world running versions of Microsoft’s Windows operating system are infected by viruses without their user’s knowledge and used to generate billions of spam emails and attacks against websites, such as that used against a British law company earlier this month.

The infected computers are often marshalled by virus writers into “botnets” which are hired out for criminal use. Microsoft, internet service providers, banks and web companies have fought long but so far unsuccessful battles against botnets. Earlier this year Microsoft took its fight to the US courts after a group of infected computers sent more than 650m spam emails to its Hotmail accounts. The spread of computer viruses has, however, continued unabated.

The new proposal, Microsoft claimed, is built on the lessons of public health. Scott Charney, corporate vice president of Microsoft’s trustworthy computing team, wrote on the company’s blog: “Just as when an individual who is not vaccinated puts others’ health at risk, computers that are not protected or have been compromised with a bot put others at risk and pose a greater threat to society.”

via Microsoft: virus-infected computers should be quarantined | Technology | guardian.co.uk.