Many of the Web giant's products are susceptible to attacks -- that's why the Web giant says it will now pay up to $20,000 for anyone to find "qualifying vulnerabilities."
A skilled hacker can probably make a lot more than that, if they want to... come on, Google. (It's mostly PR to ease users minds that Google is secure. But what about them as keepers??) I think this awareness all started back in 2010.
Anyway, here's a relevant article. Useful, too, if you use Gmail.