Facebook-owned Instagram, a site that makes it easy to share photos via smartphones, has plugged a vulnerability that a security expert claimed could allow hackers to view users' private photos.
Instagram, which Facebook bought for $1 billion in April, said in a post on its help center that the flaw, dubbed the "Friendship Vulnerability," was fixed within a couple of hours the site was notified of the problem. Instagram did not say when it was notified.
The company did not find any evidence that the vulnerability had been exploited, other than by the researcher. Instagram was vague in how the flaw could have been used, saying only that in "very specific circumstances a following relationship could be created incorrectly."
"Never in the course of the bug existing was users' data at risk -- and at no point were private photos made public," the company said in the post.
Spanish security researcher Sebastian Guerreo discovered the vulnerability this week and posted the discovery on his blog on Wednesday, after notifying Instagram, according to Stephen Cobb, a security evangelist at ESET who communicated with Guerreo by email.
By using a brute force attack, Guerreo was able to bypass Instagram's friend request mechanism, making it possible to use only a username to view someone's private photos.
"If I knew your username on Instagram, then I would be able to look at your pictures without you having to approve my request to do so," Cobb said on Thursday. "You can abuse the permission request process."
A brute-force attack is when a hacker uses software to systematically check all possible combinations of numbers, letters and symbols to discover the key to decrypt encrypted data.
Despite Instagram's claims that no accounts were compromised, the flaw indicated a "serious oversight" in the way the request mechanism was programmed, Cobb said. "It raises question about the process by which Instagram rolls out its code."
Instagram has more than 50 million users of its Android and Apple iOS apps that enable people to add retro or vintage-style filters to photos and then use their smartphones and tablets to share the pictures across multiple social networks.
Read more about social networking security in CSOonline's Social Networking Security section.