No system is 100% secure.
No-one knows how they're hacking yet, some people are saying that it's after people join their games. Other people are just saying they're guessing P/Ws.
It doesn't matter, I doubt it's Blizz's fault.
All im saying is, my system is as secure as any other user could make it. My password wasn't easy to guess i dont open stupid phiscing emails or visit dodgy websites ever. I didn't lose much gold as iv barely played it this week but it deffo wasn't a fault of mine. Also i never joined any public games i only played with friends irl.