The researchers monitored more than 10.2 million Instagram accounts - including popular Instagrammers, such as Taylor Swift and Justin Bieber - and they also purchased 20,000 fake accounts for $100 and then studied their behavior over the course of a month.
Not only did study find that 7.9% of the accounts in its sample behaved like spam bots, but the researchers discovered that 29.9% of users appear to be inactive - posting one or fewer photos or videos in a month.
Instagram declined to comment on the report.
The "Instagram spam-bots and social media popularity" study - co-authored by Andrea Stroppa, Daniele di Stefano, Matt Hofmann, and Bernardo Parrella - could potentially make for worrying reading for Instagram. In December the photo sharing app launched a crackdown on spam accounts, purging many of the bots from its system. But it seems the issue still exists.
That's a problem as Instagram steps up its advertising offerings to brands. Marketers want to know that the amount of followers they have, and engagements with their posts, are from genuine fans of the brand - and potential customers. Instagram's business model is dependent on user engagement - and inactive or spam accounts don't help its cause.
The report's abstract reads: "Despite that last December purge and new 'countermeasures' to curb this trend, there is still a lack of transparency about internal data and very few analysis on the actual presence of spambots, especially on Instagram. Now that 'anybody can advertise on the platform,' and the company is set to 'become a real business,' it is crucial to create a level playing field for everybody - and also to show more respect for users that flock social media platforms."
The research uncovered insights into how spam bots generally behave. On average, spam bots uploaded up to 6 videos or photos to Instagram and followed around 41 users for each follower they had. A real user follows just one other person for each follower, the study found.
Instagram claims to have world class technology to identify and delete accounts. But the study found that spam botnet operators have become increasingly sophisticated in bypassing Instagram's filters. The botnet operators acquire a huge amount of IP [internet protocol] addresses so it appears that new Instagram accounts are being set up from different places. They also acquire email address in bulk from major providers such as Yahoo, Hotmail. and Gmail to get past Instagram's email verification.
Instagram now boasts 300 million monthly active users. It claims not to count inactive or fake users as part of that number, and it only counts a user as part of its total user number if they are active and log in every month - but the study shows that spam bots are getting increasingly clever at looking a lot more like active users.
Instagram isn't alone in struggling to rid its community of fake accounts. Audits of Twitter followers have unearthed lots of fake accounts too. Twitter said in its Q4 earnings report that approximately 8.5% of users "used third-party applications that may have automatically contacted our servers for regular updates without any discernable additional user-initiated action." That doesn't necessarily mean they're spam accounts - they could be users of a lock screen app on a phone that receives the Twitter news feed. But pieces of software that don't really add anything to the platform aren't necessarily helping its case to advertisers either.