Matthew Garrett

Specifically, there was a tool called Dropship to "teleport" files into your own account with just the right hashes. This was of course quickly abused by people that don't respect copyright laws, as you could share a movie in like 10KB worth of hashes without ever violating copyright law as far as Dropbox was concerned. Very thankful they tried to Streisand it off the internet, it's a super interesting if usually impractical attack vector and it'd have been a shame to miss it.