Users who log onto Amazon, Facebook, Twitter, Flickr, or Google via open Wi-Fi networks are at risk of having their identities hacked due to a Firefox add-on called Firesheep, released by Seattle software developer Eric Butler at the Toorcon 12 security conference in San Diego, reports Katie Kindelan from sister blog Social Times.

The app — which Butler claims he created to expose the dangers of using public Wi-Fi networks to go online — has been downloaded nearly 50,000 times, according to Social Times.

There is a possible remedy, though, other than the obvious one of not logging on via Wi-Fi: Social Times reported that a TechCrunch user posted about another Firefox plug-in that blocks Firesheep, although the URL was not functioning at the time of this post.