Cryptorush is shitty exchange. Laggy trade engine, many complaints from traders and miners, periodically frozen btc trades/withdrawals and now this - stolen BCs.
Poloniex owner, when hacker stole 90 BTC (as I remember), was honest with members, he told whole stoly and then cut all BTC balances by 12,8%. He said, that all trading fees now going not into his pocket but to cover this loss. AFAIK, all loss have covered by now, and no one had lost nothing.
That's how business should be done.