Security researchers at Bitdefender have discovered a new phishing scam that installs a malicious extension in the Chrome web browser in order to turn Facebook 'likes' into cash for cyber crooks.
The exploit begins with a malicious link embedded in spam email, says Bogdan Botezatu, a senior e-threat analyst at Bitdefender. The link ushers you to the Chrome Web Store, where you download an extension for a "business" Flash player—assuming you're foolish enough to click on spam links.
"They can run as many campaigns as they want," Botezatu said in an interview. "All they have to do is fetch a new script."
Through the script, your account can be used to spam your friends, post malicious links on your news feed and Timeline, and automatically "like" pages without your knowledge. "They can do anything that the user can do with their Facebook account," Botezatu said.
An attacker can also steal your Facebook cookies with the malicious extension. Then the crook can use the cookies to access your account from another computer. "That's how you can lose your account," Botezatu said.
The script is also instructing compromised accounts to "like" specific pages. Once such page discovered by Bitdefender had more than 40,000 likes, although the page was devoid of content.
As those pages accumulate likes, their resale value on the Dark Net rises. As pages rack up likes, they become more visible to Facebook users. That visibility is worth hundreds of thousands of dollars to cyber crooks because it gives them a platform to target Facebook users with everything from more malware to pitches for counterfeit clothing.
"On underground forums in Russia, a page with 100,000 likes sells for about $150 to $200," Botezatu said.
Once a byte bandit buys a page, he can rebrand it. "They can make the page look as if it's affiliated with a well-known brand," he explained. "We saw one page being used to market fake Nike sportswear."
Malicious links can also be posted to the page so all visitors who like the page will display those links on their own Facebook pages, he added.
Botezatu said that it's unlikely that this kind of infection will be detected by an antivirus program, unless the program also includes web filters. "This kind of threat can persist in a browser for quite a long time," he said.
This isn't the first time that Chrome extensions have been used to work mischief on Facebook. Last spring, rogue extensions began appearing in the Google Web Store promising to allow Facebook users to do things like change the color of profile pages and remove social media viruses.