[steve86]

Google informed me in the middle of the night that another party was in possession of my Gmail, etc., username and password. This was in the form of an automated app in another state (Pennsylvania) that was attempting to login to my account (and would have, except Google intercepted it). Between 1 and 2 AM I changed all of my passwords.

It is unclear how this situation came to be. The usual obvious explanations (unencrypted hotspots and the like) don't apply, and the password should be hashed at the other end. Linux on this end, properly maintained, and no indication of anything amiss. There is nothing particularly of interest in my boring gmail, so it is puzzling that anyone would go to the trouble of computing a hash match.

[Errant]

Had an old yahoo account taken over by spammers once, along with a bunch of others who had old accounts that Yahoo kept the files of on an easily broken into server.

Someone may have gotten your info from another less secure site and just seeing if you had a gmail account using the same username/password?

[Myrddin]

No trouble. Rainbow tables. Precomputed values that match the md5 hash of your passwd. Stored “in the cloud”.

[GeronL]

hacking is a scattered approach, they have likely programmed a computer to hack hundreds or thousands of emails at a time

[Vision Thing]

To make it harder for the bad guys in the future, try using Google’s two-factor authentication. After anyone logs in successfully with your username and password, Google sends a code to you by phone, text, or email. You can proceed only if you enter that code.

With two-factor authentication, it’s much harder for the bad guys to take over your account.