Red Hat Bugzilla – Bug 1306165
GDM allows taking screenshots in locked session
Last modified: 2016-12-11 14:11:29 EST
Created attachment 1122694 [details]
Screenshot taken while the screen was locked
Description of problem:
I was surprised to find out that while my gnome-shell session was locked in GDM, it was still possible to take screenshots following specific steps.
In other words, a locked session still allow some shortcuts to call an external program.
I believe it is a security issue, even if it is a moderate one.
Anyone could flood the victim's disk with thousands of images, by keeping the [PrintScr] key pressed.
Also, if the key happened to be remapped by the user to another program, who knows what the consequence could be.
Steps to Reproduce:
1. Lock the gnome-session
2. Right click in the user password field
3. Take a screenshot by pressiong the [PrintScr] key
4. Eventually keep the key pressed if you want to flood the Picture directory of the victim
A screenshot is taken like usual and saved in the Picture folder of the active user.
See enclosure of an example screenshot.
I would expect that it is blocked like in this context menu like it is in any other part of the locked screen.
I believe it is essential that no external, background task could be launched while the screen is locked, even if the risk appears to be low at first.
I think this issue is gone on F24, at least for Gnome+Wayland sessions.
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Yes, it is gone. Let's close it.