Now imagine he's found her, and is walking her way.
Such a situation might have occurred just a few months ago to users of Tinder, a popular dating application that enables single people to find other singles who live or work in the same community. According to a report by researchers at security consulting firm Include Security, a vulnerability in Tinder's geo-location feature might have allowed a computer-savvy user to determine the location of another user within 100 feet.
"We were able to collect very precise location data from the server which, combined with the user's own location data, made it possible for any user to find the location of any other user," says Erik Cabetas, founder of Include. "It wasn't hard -- it was simple trigonometry."
Cabetas, who worked with Include researcher Max Veytsman to verify and report the vulnerability to Tinder, says the problem has now been fixed, and that Tinder's servers now give only a general area of another user, rather than a precise location.
The researchers could not say exactly how long the vulnerability existed, but they suspect it has been an issue since July of 2013, when Tinder fixed a similar vulnerability that had been disclosed by other researchers. "Tinder's fix for that first vulnerability was incomplete," Cabetas says.
In his blog about the vulnerability, Veytsman describes a small application he wrote which exposed the vulnerability and made it a simple task to geo-locate a simulated Tinder user using the data exposed by the server. Such vulnerabilities are not unique to Tinder and could be found in any other distance-aware mobile application that gives away too much location data, Veytsman says.
"Mobile applications are often the victims of bad designs, copycat applications, and malware," Cabetas says. "There are some mobile apps that are pretty solid, but for a lot of them, it's the wild west out there."
Include, a startup company that is now becoming more public after two years of quiet operations, is made up primarily of security researchers from all over the globe who help assess and find vulnerabilities in Web applications.
"We're doing a lot of work with mobile apps, and in general, we find that the more interaction involved in the app, the greater the attack surface," Cabetas says. "You can build interactive applications right if you see the security implications first, but it is a lot harder if you're going back and trying to fix an app that's already out there."
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