Instagram found itself ripe for spammers over the weekend as thousands of its members were targeted by a fruit diet company.
The campaign first reported by Om Malik at GigaOm sent images of fruit to members of the photo sharing service owned by Facebook promoting the healthy aspects of a fruit diet.
Accompanying the pictures was a link leading to a phoney BBC page promoting weight-loss coffee. The page was clean of malware and doesn't appear to have posed a danger to the 35,000 or so Instagram members who clicked on the Bitly shortened URL to get to the page.
"This likely does mark the largest single spam campaign on Instagram to date, but it remains to be seen whether this will be a one off or just the beginning," Jason Ding, a researcher at Barracuda Networks, said in an email.
"That will largely depend on how profitable the campaign was," he added.
It's not unusual for spammers to test the waters before they engage in more malicious activity. "Things like this are often proofs of concepts," Chris King, senior director of product management for Palo Alto Networks, said in an interview.
"These guys are sophisticated computer scientists," he added. "They engage in things like pilots and betas and things like that."
Following reports of the spam campaign, Instagram issued a statement declaring that it had the situation under control. "Recently, a small portion of our users experienced a spam incident where unwanted photos were posted from their accounts," it said.
"Our security and spam team quickly took actions to secure the accounts involved, and the posted photos are being deleted," it added.
GigaOm reported that users affected by the spamming received notices that their passwords had been reset and were asked to create a new password for their accounts.
[Also see: Botnets target social networks with spam]
The attack is believed to have lasted only a few hours and affected only a small portion of Instagram's 130 million users.
Instagram recently added a video service to its repertoire, which may be contributing to its attractiveness to spammers. "[T]he number of scams on Instagram is rapidly growing following the introduction of the video service, since the number of users is also rapidly increasing," Bogdan Botezatu, a senior e-threat analyst with Bitdefender, said in an email.
"At the moment," he continued, "there are a number of underground groups that specialize in Instagram account creation. They create accounts using various e-mail addresses and IP addresses and sell them for approximately $7 for 100 accounts."
"These accounts are used in an automated way to follow legit users and broaden their interaction with potential victims," he said.
Another possible entry point for spammers into Instagram is through its API. "They could have used the API to send a specific set of commands to Instagram users like any application found on Facebook or any other social network," Matt Mosley, an information security consultant with Tevora Business Solutions, said in an interview.
"They may have found a weakness in the API that allowed them to exploit it with bots," Mosley said. "Twitter had the same problem and recently updated its API to address it."
What sets this attack apart from prior spam campaigns against Instagram is that it appears to have involved hacked accounts. "These spam images were coming from legitimate users whose accounts had been compromised," said Sapnam Narang, a security response manager at Symnatec.
"That's different from the normal fake accounts that are created for the purpose of spamming," Narang told CSOonline. "We've seen that on Twitter with diet spam."
Instagram members may want to brace themselves for future spam campaigns, cautioned Ragib Hasan, an assistant professor and director of SECRETLab at the Department of Computer and Information Sciences at the University of Alabama at Birmingham.
"This shows that it's possible to spam Instagram," Hasan said in an interview. "My worry is that in the near future you'll see more malicious spamming using this kind of social media."