Google sent alerts to users whose computers appeared infected. (KIMIHIRO HOSHINO/AFP/GETTY IMAGES)

Looking into some unusual search traffic, Google suspected that computers showing the unusual behavior may have been infected with a virus.

So, on Tuesday, the company used its biggest platform to let people know — it’s search results.

Users whose computers exhibited this unusual behavior saw a banner at the top of Google’s search page. “You’re computer appears to be infected,” the banner said. “It appears your computer is infected with software that intercepts your connection to Google and other sites,” it went on before directing users to a Help File article.

In an update to its post on Wednesday, Google security engineer Damian Menscher said that he believes “a couple million” machines had already been infected by the malware, which offered a fake antivirus application that caused affected computers to send traffic to Google through intermediary proxy servers.

Menscher said that Google chose to put the notice on its search results page as a measure against having the warning targeted by hackers itself.

“Falsifying the message on this page would require prior compromise of that computer, so the notice is not a risk to additional users,” he wrote.

Web surfers should always be cautious about the links they click and the programs they choose to download. You should always pass on installing a program you didn’t choose to install yourself— even if it’s screaming at you that you’re computer is infected.

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