Bug 1124488 (CVE-2014-5118)

Summary:	CVE-2014-5118 tboot: argument measurement vulnerability for GRUB2+ELF kernels
Product:	[Other] Security Response	Reporter:	Vincent Danen <vdanen>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dcantrell, eparis, gang.wei, sbueno, sgrubb, tmraz
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	tboot 1.8.2	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-04-23 13:07:53 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:	1124489
Bug Blocks:	1124491

Description Vincent Danen 2014-07-29 15:35:35 UTC

A flaw was reported [1] in how TBOOT handled measuring arguments to ELF kernels.  When TBOOT is used on systems loading an ELF kernel, the first argument to any GRUB module may go unmeasured, which may result in undetected system compromise and violates the remote attestation that the argument measurement is intended to provide.  This is fixed [2] in upstream version 1.8.2 and it is reported that all prior versions are vulnerable.

A CVE has been requested but not yet assigned [3].

[1] http://sourceforge.net/p/tboot/mailman/message/32655538/
[2] http://sourceforge.net/p/tboot/code/ci/0efdaf7c5348701484d24562e6e5323d85bb94d3/
[3] http://openwall.com/lists/oss-security/2014/07/29/1

Comment 1 Vincent Danen 2014-07-29 15:36:09 UTC

Created tboot tracking bugs for this issue:

Affects: fedora-all [bug 1124489]

Comment 2 Vincent Danen 2014-07-30 21:32:57 UTC

This was assigned CVE-2014-5118:

http://seclists.org/oss-sec/2014/q3/260

Comment 3 Fedora Update System 2014-08-16 00:28:20 UTC

tboot-1.8.2-1.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 Fedora Update System 2014-08-16 00:30:09 UTC

tboot-1.8.2-1.fc19 has been pushed to the Fedora 19 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 5 Stefan Cornelius 2014-09-08 10:11:09 UTC

Alright, this is an interaction problem with GRUB2 (and possibly more, non-legacy-grub bootloaders). RHEL6 tboot may be vulnerable, but we don't ship GRUB2 with RHEL6, so I guess it's rather uncommon to see a vulnerable RHEL6 setup.

Comment 6 Stefan Cornelius 2014-09-08 11:53:50 UTC

Upstream patch: http://sourceforge.net/p/tboot/code/ci/0efdaf7c5348701484d24562e6e5323d85bb94d3/

Comment 8 Tomas Hoger 2015-04-23 13:07:53 UTC

The tboot packages in Red Hat Enterprise Linux 7 were updated to upstream version 1.8.2 which includes the fix for this issue (see comment 6 above) via Red Hat Enterprise Linux 7.1 erratum RHBA-2015:0584:

https://rhn.redhat.com/errata/RHBA-2015-0584.html

The issue / fix is specific to use of tboot with grub 2.  Red Hat Enterprise Linux 6 provides grub 0.97 and hence the issue is not planned to be addressed there.

Comment 9 Tomas Hoger 2015-04-23 13:13:07 UTC

Note that this issue may prevent detection of bootloader configuration change, which itself require attacker to have privileged local access.