I have not made any export
I also do not use their back up system.

I used Blockchain.info online wallet with VERY strong password (small, big letters, numbers, combinations with shift and so on).

Yesterday (2014-09-24 22:51:17) from my wallet were stolen 0.5037 BTC ($ 204.94) to wallet: 16aBR9c33aXBpGPeEiie5xFwqEx8jsSkZL


From support I got something like they are very sorry and that it can be malware or I just shared my information of login, but in this case sorry is not enough, because we are talking about safety, how it is possible that someone just hacked it?

I am using Firefox based on Windows to Login, I never ever shared login information and I also do not have any backup on my laptop of login password.