Google has begun issuing warnings to millions of people that their PC has been infected with a virus.
The malicious code pipes browser traffic through sites that promote the scammers' wares which include fake security programs. Those hit by the virus will be warned with a message that will appear at the top of searches carried out via Google.
The search firm estimates that more than two million people have been hit by the infection.
Stolen traffic Google uncovered the huge number of infected machines while doing routine maintenance on a data centre. During maintenance, Google servers get taken offline and typically this means search traffic for that cluster of machines dries up.