It isn't just bittrex it is also poloniex: https://steemit.com/steemit/@bigdeej/poloniex-no-cold-storage-for-steem-funds-usd50-million-usd-at-risk-in-hot-wallet
And I suggest sharing this post with them if you are a customer since the more people who bring it to their attention the faster it can be fixed. In less than 2 hours this could be fixed and a cold storage setup! At most 1 day! The solutions are simple and something that are very well known in the crypto security industry. The only option is to force them to fix it by publicly disclosing their flaws! Anyone who uses them could easily figure this information out. Hackers already know, they just haven't gotten through (yet)! I advise exchanges not to wait till it does happen before implementing cold storage procedures and policies!