[Bug 1803993] Re: Password appears on the VT1 screen
Daniel van Vugt
daniel.van.vugt at canonical.com
Tue Nov 20 03:34:11 UTC 2018
^^^
That is probably just to verify this really isn't a duplicate of bug 1767918, and that you have the fix for bug 1767918 already.
** Summary changed:
- GDM is Exploitable as a Password Collector
+ Password appears on the VT1 screen
** Changed in: gdm3 (Ubuntu)
Status: New => Incomplete
** Also affects: plymouth (Ubuntu)
Importance: Undecided
Status: New
** Changed in: plymouth (Ubuntu)
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1803993
Title:
Password appears on the VT1 screen
Status in gdm3 package in Ubuntu:
Incomplete
Status in plymouth package in Ubuntu:
Incomplete
Bug description:
This was found when an administrative error made /home directory
inaccessible. Any users that tried to login after that, were not able
to (which is expected) but their password appears on the VT1 screen.
Under normal circumstances, VT1 is not visible. But once the system
was sent into this compromised mode, one can press ctrl+alt+F1 and
then ctrl+alt+F2 and get a momentary glance at VT1. One can keep
toggling between these key combinations in order to make out the
password(s) on VT1.
As a further test, I wanted to see if a non-super user could cause
this condition, and it is in fact possible. As a regular user, I made
their own home directory not writable and then removed ~/.config and
logged out. Then logged in as that user again, and although that user
can't login the system does go into that mode where passwords appear
on VT1 and are viewable with the key combinations mentioned herein.
Further, any other users that login will see no problem, but when they
logon their passwords also appear on VT1 and are viewable.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.3-0ubuntu18.04.3
Uname: Linux 4.19.2-041902-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Nov 19 08:32:59 2018
InstallationDate: Installed on 2018-08-25 (85 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)
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