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The task is: Prevent the ability to take screenshots on an 6.0.x android OS globally. What I mean by "globally" is to exclude that function and block it completely so that even if the device is to be infected with a screenshot-taking malware it should not be able to do so. I am interested in screenshot-prevention in all apps and even when no apps are running, everywhere. Thanks in advance!

upd. I am really sorry if that question is not stated clearly but I thought I could find some help here at least some points in the direction I should look for. I think this question will be useful for others too if answered.

  • As long as the malware/app has not root access, the command wm screen-capture 0 false would do the job on Android 6.0.x. – Firelord Oct 12 '16 at 15:24
  • Thanks. Where should I execute that? In the console? – DedToto Oct 12 '16 at 15:32
  • I have a rooted device and still in the console it says "java.lang.SecurityException: Only system can call ScreenCaptureDisabled." – DedToto Oct 12 '16 at 15:40
  • Do su 1000 -c 'wm screen-capture 0 false'. – Firelord Oct 12 '16 at 15:58
  • Big thanks! One more question please: In order to reverse that command an attacker needs root access? And in case I have an Xposed module that sets permission for each and every new app manually this is less likely to happen? – DedToto Oct 12 '16 at 16:12
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If the Android is rooted and is version 6.0 or above, then using console or , execute:

su 1000 -c 'wm screen-capture 0 false'

where:

  • su 1000 -c - switch to user with ID 1000 (System user) and execute the following command
  • 0 - user ID of the primary user of the device.

Now, whenever you or any app would attempt to capture the screenshot using the standard means in Android, a notification with title Couldn't capture screenshot would show up.

However, as long has the malware/app can gain root access or system level privilege or becomes a member of the user group graphics (through an exploit or other means), all restrictions would be in vain since the malware/app can access framebuffer. For details, follow: Why do we need a rooted phone to capture screenshots on older versions of Android?

  • Thanks. It worked perfectly but I have another related question: I've executed that command but right after the phone restart it doesn't work anymore and I have to type it in again. Is there a way to execute it at OS startup? – DedToto Oct 12 '16 at 16:44
  • You can use an automation app, such as Tasker to do that for you. And thanks for mentioning that issue. I wasn't aware of it. – Firelord Oct 12 '16 at 16:51
  • Yeah I just realised how serious is that problem when I witnessed a court case where such screenshots were brought as evidence against a man that used a secure chat and message trimmering. – DedToto Oct 12 '16 at 16:58

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