The site is at http://www.snapchatdb.info/ and lets you download the information as a SQL dump and as CSV text.
What am I downloading?
You are downloading 4.6 million users' phone number information, along with their usernames. People tend to use the same username around the web so you can use this information to find phone number information associated with Facebook and Twitter accounts, or simply to figure out the phone numbers of people you wish to get in touch with.
Some more information...
This database contains username and phone number pairs of a vast majority of the Snapchat users. This information was acquired through the recently patched Snapchat exploit and is being shared with the public to raise awareness on the issue. The company was too reluctant at patching the exploit until they knew it was too late and companies that we trust with our information should be more careful when dealing with it. For now, we have censored the last two digits of the phone numbers in order to minimize spam and abuse. Feel free to contact us to ask for the uncensored database. Under certain circumstances, we may agree to release it.
Last month, ZDNet reported that Gibson Security had published undocumented developer hooks (API) and code for exploits that allow mass matching of phone numbers with names and mass creation of bogus accounts after Snapchat had ignored their security disclosure since August.
According to the leak, the exploit has recently been patched; however, this probably won't give users on the list much comfort.
Developers Robbie Trencheny and Will Smidlein have created a reverse lookup tool that lets you input your username to see if your account was hacked.
Snapchat has yet to issue a statement. Please follow iClarified on Twitter, Facebook, Google+, or RSS for updates.
Update: Snapchat has issued the following statement regarding the breach:
When we first built Snapchat, we had a difficult time finding other friends that were using the service. We wanted a way to find friends in our address book that were also using Snapchat — so we created Find Friends. Find Friends is an optional service that asks Snapchatters to enter their phone number so that their friends can find their username. This means that if you enter your phone number into Find Friends, someone who has your phone number in his or her address book can find your username.
We acknowledged in a blog post last Friday that it was possible for an attacker to use the functionality of Find Friends to upload a large number of random phone numbers and match them with Snapchat usernames. On New Years Eve, an attacker released a database of partially redacted phone numbers and usernames. No other information, including Snaps, was leaked or accessed in these attacks.
We will be releasing an updated version of the Snapchat application that will allow Snapchatters to opt out of appearing in Find Friends after they have verified their phone number. We’re also improving rate limiting and other restrictions to address future attempts to abuse our service.
We want to make sure that security experts can get ahold of us when they discover new ways to abuse our service so that we can respond quickly to address those concerns. The best way to let us know about security vulnerabilities is by emailing us: firstname.lastname@example.org.
The Snapchat community is a place where friends feel comfortable expressing themselves and we’re dedicated to preventing abuse.