"Hey guys, just got a PM from a buddy who's a white-hat dev. He's dealing with a cracked DB that's got a mysterious SQL injection exploit happening. Anyone else dealt with something like this or got some tips on how to track down the source?"
"Dude, this looks like a textbook example of a SQL injection attack, probably from a poorly sanitized user input. Have you checked the server logs for any suspicious activity prior to the breach? Also, are you guys using prepared statements in your queries?"
"Lol @OP, SQLi is so 2010. Anyway, since you've got a cracked DB, have you tried running a SQL query to see if you can get a list of user accounts or any other sensitive info?"