Bug 1515198 (CVE-2017-16837)

Summary:	CVE-2017-16837 tboot: Incorrect validation of certain function pointers
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dcantrell, eparis, gang.wei, tcamuso
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-12-21 07:06:29 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1515199
Bug Blocks:	1515202

Description Andrej Nemec 2017-11-20 11:37:28 UTC

Certain function pointers in Trusted Boot (tboot) through 1.9.6 are not validated and can cause arbitrary code execution, which allows local users to overwrite dynamic PCRs of Trusted Platform Module (TPM) by hooking these function pointers.

References:

https://sourceforge.net/p/tboot/code/ci/521c58e51eb5be105a29983742850e72c44ed80e/

Comment 1 Andrej Nemec 2017-11-20 11:37:59 UTC

Created tboot tracking bugs for this issue:

Affects: fedora-all [bug 1515199]

Comment 2 Doran Moppert 2017-12-21 07:06:29 UTC

The main issue here is an "evil maid"-style attack, where the attacker has physical access to the target machine and uses this to modify /boot/tboot.gz to run arbitrary code at boot time.  This could be a concern if disk encryption keys are stored sealed in the TPM .. but in this scenario there are lots of other attack vectors (physical/hardware as well), so I see no urgency to fix this.