Bug 631164 (CVE-2017-12164)

Summary:	<gnome-base/gdm-3.22.3-r1: lock screen can be circumvented when autologin is set
Product:	Gentoo Security	Reporter:	Christopher Díaz Riveros (RETIRED) <chrisadr>
Component:	Vulnerabilities	Assignee:	Gentoo Security <security>
Status:	RESOLVED FIXED
Severity:	normal	CC:	gnome
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
URL:	https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-12164
Whiteboard:	~4 [noglsa cve]
Package list:		Runtime testing required:	---

Description Christopher Díaz Riveros (RETIRED) gentoo-dev

2017-09-16 23:02:18 UTC

From URL:

The gnome lock screen can be unlocked without needing a password. 

Steps to Reproduce:
1. Enable Automatic Login for your account
2. Reboot
3. Lock screen
4. Click on the log in as another user button below the password prompt.

Actual results:
The screen unlocks without a password being entered.

Expected results:
A selection of other accounts is shown.

Comment 1 Mart Raudsepp gentoo-dev

2017-09-16 23:20:49 UTC

Help welcome identifying if 3.22.3-r1 is vulnerable or not. I believe 3.24.3 is fixed already (double checking appreciated, but gnome distro-list e-mail, NEWS item and Gilles' commit says as such), but we can't stable that just yet, so need to make sure 3.22.3-r1 is safe or needs patching.

Comment 2 Mart Raudsepp gentoo-dev

2017-09-16 23:22:29 UTC

distro-list e-mail said:

"Anyone shipping GDM 3.24.1 or later should consider upgrading to 3.24.3 
(or 3.26.0) which fixes a security hole. namely, if the user enables
autologin, then screen lock can be bypassed by trying to initiate user
switching."

So I hope that implies 3.24.3-r1 is safe, and we don't actually have anything to do here, only 3.24.2 cleanup.

Comment 3 Mart Raudsepp gentoo-dev

2017-09-16 23:24:16 UTC

argh, typo, to be clear I meant "I hope that implies _3.22.3-r1_ is safe"

Comment 4 Christopher Díaz Riveros (RETIRED) gentoo-dev

2017-09-17 16:48:54 UTC

Tried to reproduce the issue, we are ok with gdm-3.22.3-r1.

Changing whiteboard to cleanup and reassigning severity. 

@Maintainers, Please let us know when tree is clean.

Thanks,

Gentoo Security Padawan
ChrisADR

Comment 5 Aaron Bauman (RETIRED) gentoo-dev

2018-01-25 00:51:34 UTC

Tree is clean