@awokd On Sunday, February 11, 2018 at 1:37:58 PM UTC+1, awokd wrote: > On Sun, February 11, 2018 12:01 pm, Yuraeitha wrote: > > > Quote: > > "Why is full screen mode potentially dangerous? > > If one allowed one of the VMs to “own” the full screen, e.g. to show a > > movie on a full screen, it might not be possible for the user to know if > > the applications/VM really “released” the full screen, or if it has > > started emulating the whole desktop and is pretending to be the trusted > > Window Manager, drawing shapes on the screen that look e.g. like other > > windows, belonging to other domains (e.g. to trick the user into entering > > a secret passphrase into a window that looks like belonging to some > > trusted domain)." /quote-end. > > I think this is saying that when you run an application full screen, it > could pretend to act like Qubes and draw fake applications to trick you > into thinking you weren't running the application any more, but your > desktop. > > It shouldn't have any access to other windows though, even in full screen.
Indeed, it seems like this must be the case. If so, it seems to be a case where an attacker needs to fill in potentially lacking information to pull off an attack on the screen, in order to social engineer and trick people into typing sensitive information on the screen in a fake window. Still though, this is completely undone if the control of the screen is taken back by dom0. So it should be impossible to do this once fullscreen is withdrawn, which usually happens when a person stops watching a movie or stream. - I suppose it can still be harmful if alt+tab out of fullscreen without stopping fullscreen. - or if a legit popup of whatever kind appears and a person forgets about the fullscreen in the background and leaves it running. - or if multiple of monitors, and its fullscreen on one of them, can it then reach the other monitors? But is it really like this though? How does it work here, does a fullscreen still have control of the fullscreen if it's put in the background behind other non-fullscreen windows? In this case, if true, it would give an attacker the ability to control the screen and make whatever appear on it, even if it's in the background or maybe even if on another screen while working on a second screen. Would an attacker be able to make changes to the work screen which isn't in fullscreen mode? But I suppose whichever case it is, it hardly matters if a person always remembers to take back fullscreen with action from dom0, so that the AppVM looses its ability irregardless of what kind of attack is going on in the AppVM. But it would be interesting to know if a fullscreen window can keep drawing pixels on the screen, even if it's for whatever odd reason has been put in the background etc. while still in fullscreen mode. -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/adcb7955-0d80-4c14-bc65-e605c5f0d0fc%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
