they have your phone number. when you register forl%'ú snap you put in your phone number and it can go in anyone's contact file and they will know you're on snapchat. this group says it's doing it to raise awareness a loophole in snapchat and allows hackers to get in there. this hacker group is saying security and privacy shouldn't be a secondary goal. they put out a statement saying the company wasp9r& too reluctat patching the exploit until they knew it was too late and companies we trust with our information should be more careful when dealing with it. interesting. the rumor has been out that this loophole has been available on snapchat. in fact, snapchat had its own statement around8?rvñ christmas the rumors were flying and they said over last year, we have implemented safeguards to prevent this and we continue to make improvements to combat spam