Yes, it is really possible, and lost 0,08
BTC that way, only 16$ at that time, but much more now. However, since I placed a password to my wallet (yeah, was pretty stupid to don't put one : I thought I'd have to enter it each time I would get into my wallet

), never had any problem

!
That is not a big amount of money, but is never fun to get hacked and lost your money. If someone has access to your PC or your smartphone with a virus or malware, for sure he can access and transfer the fund to another bitcoin adresse.
Always a good idea to implement the basic security into your wallet

Possibility is possible as long as you're connected to internet many hackers will posibly hack your wallet because money is always involved. Best thing to do is to installed strong security on your pc or mobile phones and seek good advice from experts for your safety. Most importantly do not share to anyone your wallet password because it is the most reason for your account to become unsecured.