[Solved]18.2 Sonya guest account accesses documents and pictures
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[Solved]18.2 Sonya guest account accesses documents and pictures
After upgrading to Mint 18.2 I was curious to try the guest account that's available automatically.
A nice feature - but to my surprise, in that account it was possible to go to some files in /home/pc_owner/pictures and also in /home/pc_owner/downloads.
Isn't the home of the pc-owner supposed to be protected from access 100 %?
It's no major issue for me - just curious to learn more
A nice feature - but to my surprise, in that account it was possible to go to some files in /home/pc_owner/pictures and also in /home/pc_owner/downloads.
Isn't the home of the pc-owner supposed to be protected from access 100 %?
It's no major issue for me - just curious to learn more
Last edited by LockBot on Wed Dec 28, 2022 7:16 am, edited 2 times in total.
Reason: Topic automatically closed 6 months after creation. New replies are no longer allowed.
Reason: Topic automatically closed 6 months after creation. New replies are no longer allowed.
Re: 18.2 Sonya guest account accesses documents and pictures
Check the permissions on your folders and files.
Re: 18.2 Sonya guest account accesses documents and pictures
Yes, this should not be possible. Also I cannot reproduce it.catch22 wrote:Isn't the home of the pc-owner supposed to be protected from access 100 %?
Please describe the exact steps, which brought you to the main account.
Re: 18.2 Sonya guest account accesses documents and pictures
Simply in Nemo I went to /home/myaccount/ and started trying if it was full proof.Cosmo. wrote:Please describe the exact steps, which brought you to the main account.
The Dropbox and most other folders were secure - permission denied - but Documents let me have access to a LibreOffice odt file.
In terminal I started mocp and could play audio files that are in the Downloads folder.
In Pictures I could see all pics there. Not much to describe - it was plain open.
Re: 18.2 Sonya guest account accesses documents and pictures
Check the permissions on your folders and files.
Re: 18.2 Sonya guest account accesses documents and pictures
In the starting post you wrote, that this is an upgraded system. How did you upgrade exactly? I ask, because the official upgrade path is only open since a few hours.
How did you install LightDM (in case of an official upgrade).
And again: You wrote, that you went in Nemo to /home/myaccount. If I do this I get a popup, that because of missing permissions Home cannot be displayed, if I try to enter the path /home/user-name/Downloads or /home/user-name/Pictures I get the same. (Tests done with a fresh install of LM 18.2.)
So in case you have found a bug, we need a way to reproduce it.
How did you install LightDM (in case of an official upgrade).
And again: You wrote, that you went in Nemo to /home/myaccount. If I do this I get a popup, that because of missing permissions Home cannot be displayed, if I try to enter the path /home/user-name/Downloads or /home/user-name/Pictures I get the same. (Tests done with a fresh install of LM 18.2.)
So in case you have found a bug, we need a way to reproduce it.
Re: 18.2 Sonya guest account accesses documents and pictures
The upgrade was from Mint18.1 via the Update Manager.Cosmo. wrote:In the starting post you wrote, that this is an upgraded system. How did you upgrade exactly? I ask, because the official upgrade path is only open since a few hours.
How did you install LightDM (in case of an official upgrade).
And again: You wrote, that you went in Nemo to /home/myaccount. If I do this I get a popup, that because of missing permissions Home cannot be displayed, if I try to enter the path /home/user-name/Downloads or /home/user-name/Pictures I get the same. (Tests done with a fresh install of LM 18.2.)
So in case you have found a bug, we need a way to reproduce it.
The lightdm I installed via instructions on the blog, like so:
Code: Select all
apt install slick-greeter lightdm-settings
Code: Select all
apt remove mdm
Re: 18.2 Sonya guest account accesses documents and pictures
I have in the meantime upgraded a 18.1 system to 18.2 and installed LightDM. I confirm this problem and have opened an issue about this. This problem does only exist in upgraded systems, not in fresh installs of 18.2, so it was never possible to test this during the beta phase.
Re: 18.2 Sonya guest account accesses documents and pictures
JerryF wrote:Check the permissions on your folders and files.
Guest-Session has AppArmor profile.MintBean wrote:Check the permissions on your folders and files.
Re: 18.2 Sonya guest account accesses documents and pictures
Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)
Re: 18.2 Sonya guest account accesses documents and pictures
Thanks for the info.laederlappen wrote:Guest-Session has AppArmor profile.
Re: 18.2 Sonya guest account accesses documents and pictures
How do I disable this guest account?Cosmo. wrote:Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)
When i go to Administration / Users and Groups it's not there!
I see my own account plus a guest account that I made myself previous to the upgrade.
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Re: 18.2 Sonya guest account accesses documents and pictures
Menu - Administration - Login Windowcatch22 wrote:How do I disable this guest account?Cosmo. wrote:Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)
When i go to Administration / Users and Groups it's not there!
I see my own account plus a guest account that I made myself previous to the upgrade.
Set the switch to OFF for: Allow guest sessions
Reboot.
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Re: 18.2 Sonya guest account accesses documents and pictures
ThanksPjotr wrote: Menu - Administration - Login Window
Set the switch to OFF for: Allow guest sessions
Reboot.
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Re: 18.2 Sonya guest account accesses documents and pictures
Maybe this could be a workaround, until there's a fix? In all of the other accounts:Cosmo. wrote:Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)
Code: Select all
chmod -v 700 $HOME
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Re: 18.2 Sonya guest account accesses documents and pictures
Works.Pjotr wrote:Maybe this could be a workaround, until there's a fix? In all of the other accounts:Cosmo. wrote:Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)Code: Select all
chmod -v 700 $HOME
Seems like 18.2 upgrade doesn't install AppArmor profile which 18.2 iso has.
[EDIT]
After testing 18.2 upgrade and 18.2 iso in a VM, I can confirm that both versions have lightdm-guest-session AppAmor profile.
However in 18.2 upgrade, I couldn't run command aa-status because package apparmor was not installed.
Then I installed apparmor in 18.2 upgrade and after rebooting the system, the profile lightdm-guest-session gets loaded and guest-session works as intended.
Last edited by laederlappen on Tue Jul 04, 2017 7:06 pm, edited 1 time in total.
Re: 18.2 Sonya guest account accesses documents and pictures
Correct, but in this case we don't need a guest account.Pjotr wrote:Maybe this could be a workaround, until there's a fix? In all of the other accounts:Cosmo. wrote:Users of an upgraded 18.2 should at now not switch to LightDM or at least disable the guest account at once. This is a serious security hole in case of a local attacker. (Fresh installs of 18.2 are not affected.)Code: Select all
chmod -v 700 $HOME
It is not the task of the users to fix a security hole, this is the task of the dev team (which did not respond in 24 hours).
@laederlappen:
Might be something in this direction. But the file /etc/apparmor.d/lightddm.guest.session does exist in both systems (the upgraded and the fresh installed) and they are identical. There are indeed some differences in /etc/apparmor and /etc/apparmor.d (which possibly should not exist), but surely not all of them are related to this bug and this makes investigating difficult. (E. G. One difference concerns Firefox, what has surely nothing to do with the guest account; but possibly another leak. I am not sure about this, but I am astonished about the difference.)
So for now I warn against switching to lightdm in an upgraded system!
Re: 18.2 Sonya guest account accesses documents and pictures
@cosmo
I edited my previous post when you wrote your answer.
I edited my previous post when you wrote your answer.
Last edited by laederlappen on Tue Jul 04, 2017 7:34 pm, edited 2 times in total.
Re: 18.2 Sonya guest account accesses documents and pictures
I confirm. apparmor is missing. This is either a bug in the upgrade mechanism or in the advice to switch to lightdm. I assume the first case.
There might be some reasons, why Clem left apparmor out in the upgrade process (like he did for lightdm), but in this case there would be the clear mistake in the instructions regarding lightdm, that also apparmor needs to get installed.
I confirm also, that after installing apparmor the guest session behaves as expected.
There might be some reasons, why Clem left apparmor out in the upgrade process (like he did for lightdm), but in this case there would be the clear mistake in the instructions regarding lightdm, that also apparmor needs to get installed.
I confirm also, that after installing apparmor the guest session behaves as expected.
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Re: 18.2 Sonya guest account accesses documents and pictures
It's not a bug in the upgrade mechanism, because that doesn't install LightDM in the first place.... It's apparently an omission in the how-to in the blog, for installing LightDM *after* the upgrade.
This is the current instruction:
Apparently it should be:
So I think a simple correction of the blog post announcing the availability of the upgrade path, should suffice.
This is the current instruction:
Code: Select all
apt install slick-greeter lightdm-settings
Code: Select all
apt install slick-greeter lightdm-settings apparmor
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