Kylie Jenner, Kim Kardashian West, and Kendall Jenner attend The 2019 Met Gala Celebrating Camp: Notes on Fashion at Metropolitan Museum of Art on May 06, 2019 in New York City.

Brands pay billions of dollars globally a year to promote their products through influencers who have sizable followings on top social media sites. But a new report suggests that, for a good chunk of their spending, those advertisers are getting ripped off.

Influencer marketing gives brands of all sizes a way to reach relevant audiences on platforms such as Instagram, Snapchat or YouTube in a way that might feel more authentic to a consumer. To appear more influential than they actually are, influencers can buy fake followers and pay for bots to like or comment on their posts.

That fraudulent activity is costing advertisers $1.3 billion this year, according to a report from Cheq, a cybersecurity company focused on the digital media space, and University of Baltimore economist and professor Roberto Cavazos.

The fraud figure represents about 15% of what the report predicts will be an $8.5 billion market this year in spending on global influencer marketing. Cheq derived the amount of expected fraud through an analysis of its own data, a review of services that exist to provide fake social media engagement, and research and surveys on the subject, said Daniel Avital, Cheq's chief strategy officer. The analysis was part of a series of reports Cheq is publishing on the monetary cost of bad actors on the internet.

Having social media influence can be lucrative. According to the Cheq report, a "micro influencer" with 10,000 followers can make $250 for a sponsored post, while someone with a million or two followers can make $250,000 per post. Even individuals with 500 followers can get cash for posts. Followers don't necessarily mean sales, though, as one Instagram star recently discovered. Arianna Renee, who has 2.6 million followers, recently tried to launch a clothing line but had to scrap it after selling very few products.