Cybercriminals behind a crude but effective campaign to spread malware on Facebook are have tricked thousands of the social network’s users into installing a malicious extension on Google’s Chrome store.
Late last month, scammers were spreading photos posing as videos on Facebook that promised NSFW content but ultimately led targets to a page outside of the social network where targets were prompted to install a Flash Player update — which was actually malware — to view the video.
At the time CSO Australia reported the scam, the scammers had attracted 5,000 Facebook users to the page hosting the malicious file over a single weekend. Within days, the number of people who’d walked into the trap had climbed to over 100,000. The promise of free porn, it seems, is enough for some to drop their guard.
Targets were lured to the malicious site after being tagged in a Facebook photo, which purported to be a video. Once the user clicked on the supposed video, they were taken to the malicious website.
The same group, or possibly copycats, were at it again this weekend with the same basic modus operandi: targets are tagged in a titillating photo presented as a video and if they click on the image, they’re taken to a malicious website outside of Facebook.
This time however, the attackers have a few more tricks up their sleeves to build a network of compromised computers.
The links on Facebook are from the virtual private network (VPN) provider Hide My Ass, and victims are taken to a Facebook clone, according to Bogdan Botezatu, a malware researcher at security firm, BitDefender.
The campaign also only targets desktop systems running Google’s Chrome browser. That means PCs running Windows and OS X are in the attacker’s scope, where as mobile devices running Android and iOS are not.
According to Botezatu, 4,200 Chrome store users to date have installed one of three extensions that effectively turn affected browsers into recruitment machines.
“The addons themselves are the ones propagating the scam to victims. Since they reside in the browser, these extensions can perform any actions on behalf of the user, such as reading and modifying the data on the websites the user accesses,” wrote Botezatu.
All three of extensions remain on the store at the time of writing however BitDefender has reported them to Google.
One of the malicious extensions is “Kotsky” is aimed at users of Russia’s Facebook, vKontakte, and another, called SmartVideo for YouTube, promises to improve video on slow connections. Links to the malicious extensions can be found at BitDefender's blog.
Botezatu added that comments in the code suggested the hacker group behind the campaign is from Albanian origin.
It's not the first time malicious extensions have caused problems for Chrome users, but the Chrome store is a key tool in Google's fight against them. Last year, Google restricted extensions on Chrome to only those that were hosted on its Chrome store.Read more: Australians will sacrifice privacy for a good app and worry too little about mobile viruses
But in response to Google's move, hackers simply started hosting their malicious extensions on the Chrome store.