Bug 1147917 (CVE-2014-7300)

Summary:	CVE-2014-7300 gnome-shell: lockscreen bypass with printscreen key
Product:	[Other] Security Response	Reporter:	Vasyl Kaigorodov <vkaigoro>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	fmuellner, jrusnack, otaylor, samkraju
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	It was found that the Gnome shell did not disable the Print Screen key when the screen was locked. This could allow an attacker with physical access to a system with a locked screen to crash the screen-locking application by creating a large amount of screenshots.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-03-06 10:05:21 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1149039, 1154107
Bug Blocks:	1121513, 1147918

Description Vasyl Kaigorodov 2014-09-30 09:57:11 UTC

It was discovered [1] that PrtSc key is not disabled when the screen is locked.

Taking a bunch of screenshots at once bloats gnome-shell to the point
where it's pretty easy to get it targeted by the kernel's oom-killer.
This means that anyone with access to the keyboard of a locked GNOME
session can (briefly) disable the lockscreen, which lets them see and
interact with the running gnome session.

This might be fixed in gnome-shell 3.14.1, some patches available in the original bugreport [1].

[1]: https://bugzilla.gnome.org/show_bug.cgi?id=737456

Comment 1 Murray McAllister 2014-10-03 02:17:43 UTC

Created gnome-shell tracking bugs for this issue:

Affects: fedora-all [bug 1149039]

Comment 2 Vasyl Kaigorodov 2014-10-06 11:00:52 UTC

CVE-2014-7300 was assigned for:

"PrtSc is an unauthenticated request that's available to untrusted
parties. A series of requests can consume a large amount of memory.
The combination of this PrtSc behavior and the existence of the
oom-killer allows authentication bypass for command execution.
Therefore, the product must limit the aggregate memory consumption of
all active requests, and the lack of this limit is a vulnerability."

http://seclists.org/oss-sec/2014/q4/91

Comment 3 Fedora Update System 2014-10-18 16:58:09 UTC

gnome-shell-3.10.4-9.fc20 has been pushed to the Fedora 20 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 4 errata-xmlrpc 2015-03-05 13:21:57 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:0535 https://rhn.redhat.com/errata/RHSA-2015-0535.html