By Lorenzo Franceschi-Bicchierai From Mashable

Think twice before buying those shiny — yet extremely cheap — Ray Ban glasses advertised on Facebook. There’s a chance they’re fake.

At least, that’s the conclusion of a new study by two cybersecurity researchers who examined more than a thousand Facebook ads and found that almost a quarter of those promoting fashion and luxury goods are for counterfeit items such as Ray Bay sunglasses, Louis Vuitton bags, and Ralph Lauren polo shirts.

At first sight, the ads look legitimate and lead to websites that look like real ones, the researchers warned, potentially tricking average Facebook users into believing they’re buying real products without realizing the danger.

“You don’t know where you’re going to end up,” Andrea Stroppa, one of the researchers, told Mashable. “And in many cases your credit card is at risk, thanks to obscure payment systems backed by companies you have no idea who they are.”

Stroppa and Agostino Specchiarello set up 12 dummy Facebook accounts and identified a sample of 1,067 ads. The two researchers focused on the 180 fashion and luxury ads in that sample, 43 of which pointed to websites selling counterfeit goods, according to the study.

Those sites were set up using various techniques to trick visitors, according to the researchers. They often had legitimate looking URLs, such as www.rayban-ireland.com, and even included fake logos of security and payment system companies.

Many of those domains, according to the research, were registered in China, and their apparent owners used Chinese email accounts. And while it’s impossible to prove these sites are run by Chinese organizations, the researchers wrote, there are various clues pointing in that direction.

The researchers argue that the social network is responsible for protecting its users, despite the advertisements’ verisimilitude and difficulty to detect.

“Facebook should do more, and must do more against this,” “Facebook should do more, and must do more against this,” Stroppa told Mashable.

Facebook said that the company does all it can to remove illegitimate ads and monitor removal requests, but declined to answer some specific questions.

“We prohibit fraudulent or misleading claims or content, and to enforce our terms and policies, we have invested significant resources in developing a robust advertising review program that includes both automated and manual review of ads,” a Facebook spokesperson told Mashable.

It’s hard to tell how many ads are actually fake on Facebook, and how many of those get removed, since the company doesn’t publish this kind of data. Google, for example, removed more than 350 million “bad ads” in 2013, and almost 220 million in 2012, according to the company’s own transparency report.

The researchers, however, noted that since they started researching the issue, many of the illegitimate ads have been removed.

For the record: The study found that 24% of fashion and luxury ads sampled —not all ads on Facebook— were for counterfeit goods.

This story has also been updated to reflect the fact that some of the illegitimate ads analyzed by the researchers have since been removed

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