I also had an unauthorized transaction yesterday, I've been using blockchain for about 2 years now and have never had this problem before. I talked to support and they said i either had malware or used a phishing site. I'm using Ubuntu so I don't think malware is the problem, I was in a hurry when i logged in but i tried to look for phishing sites by doing a search and couldn't really find any( i also just made this wallet). The only other thing i did was use tor while creating this wallet(for anonymity) not sure if thats what did it, but I've done this multiple times before with no problem. Guess this is just the nature of the btc game, i should have set a secondary pass maybe? any insight would help for future transaction. this is the wallet for reference 1CDAeLd55L4o9ivYGHsH2JecB3HfRgVKYt