Nasty Google Drive Permissions Bug


The Blog of Tom Webster

  2015-02-05 18:26:00 PST

As some of you know, I co-host Security:inThirty with Chaim Cohen. We get emails from time to time from listeners with questions, comments, and stories. One frequent listener informed us about a very strange security problem they were running into with Google Drive: They can access someone else's files, even though they haven't this user hasn't shared anything with them.

As strange as this issue seems at first glance, I couldn't dismiss it as user error, as I had seen the same thing once in the past myself, and have read about it happening in a few other instances. The user in question is Gunnar Haid, he's technically apt and security aware. This isn't user error (at least on his part), and I doubt this is human error by the other user either (more on this in a bit). This problem isn't widespread (as far as I can tell), but other Drive permissions bugs have been very prevalent in the community (such as being unable to delete files you own).

I was sent an email thread and several screenshots detailing the problem. I am not releasing either in the interest of privacy (most screenshots would need to be heavily censored, removing the point of posting them). The first thing Gunnar did was contact Google support, the right move. One support rep was convinced that the other user had marked their files as "public on the web", this is not the case. Gunnar has provided screenshots showing file permissions that list only the owner has access and that link sharing is disabled. Gunnar was then passed around to a couple other support reps, running in circles trying to explain the same issue, to no avail. As it stands today, Google requested (and has received) screenshots, but has not responded to the issue since October 1st 2014.

The user in question who is having their data leaked by this bug is very technical as well. They have several websites and work in a tech-based field. The filenames also lend me to believe this person is very technical and working with advanced tech (for non-tech people, anyway). For obvious reasons, I can't go into personal details beyond that, but needless to say, this user is also very technically apt.

This isn't a case of user error, this looks like a pretty serious bug that Google needs to take a hard look into. The big issue here is someone's files are completely accessible by someone else who has no relation to the user. Our show has a small (but dedicated) following and it makes me wonder how widespread this issue is. It doesn't seem widespread, but I have no way of knowing for sure. If Google would comment on the issue, I'll be more than happy to post the response, at the moment, I'm only concerned with getting this fixed and figuring out why it happened in the first place.