The most dangerous virus to have infiltrated Facebook was created by a collective of hackers from St. Petersburg, according to the social network’s security team.

The hackers, known as the Koobface gang, sent Facebook users attractive invitations to watch a funny or sexy video. When the unsuspecting users clicked the link, the message appeared saying that their computer’s Flash software needed updating. The “update” was in fact malware that hijacked the user’s clicks and delivered them to advertisers, making the hackers money -to the tune of over $2 million annually, the New York Times reports..

The network of infected computers included between 400,000 and 800,000 PCs, according to cyber security firm Kaspersky Labs.

What outraged the Facebook security team the most is that the hackers did not even care to hide their activities. The group openly lives in St. Petersburg posting photos of their expensive travels to such places as Monte Carlo and Bali.

“They could have stolen passwords and hacked into private information, could have stolen credit card details,” Sergey Golovanov, expert at Kaspersky Lab, told RT. “Rather than that, they used the virus to tweak search results and place advertisements. It's very difficult to bring about a legal action because technically there is no victim. That's unless someone goes to the police with a complaint.”

This not is the first high-profile cyber crime involving Russian hackers. Back in October 2010, six young Russians were accused of involvement in a major computer hacking scam against US banks.

The accused – all in their early to mid twenties – were charged with stealing $3 million from back accounts with the help of a computer virus.