Bug 1515198 – CVE-2017-16837 tboot: Incorrect validation of certain function pointers

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Bug 1515198 - (CVE-2017-16837) CVE-2017-16837 tboot: Incorrect validation of certain function pointers

Summary:	CVE-2017-16837 tboot: Incorrect validation of certain function pointers

Status:	CLOSED WONTFIX

Aliases:	CVE-2017-16837

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
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Assigned To:	Red Hat Product Security
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Whiteboard:	impact=moderate,public=20171113,repor...
Keywords:	Security

Depends On:	1515199
Blocks:	1515202
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Reported:	2017-11-20 06:37 EST by Andrej Nemec
Modified:	2017-12-21 02:06 EST (History)
CC List:	4 users (show)

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Last Closed:	2017-12-21 02:06:29 EST
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Description Andrej Nemec 2017-11-20 06:37:28 EST

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 06:37:59 EST

Created tboot tracking bugs for this issue:

Affects: fedora-all [bug 1515199]

Comment 2 Doran Moppert 2017-12-21 02:06:29 EST

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.

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