Bug 1343505 (CVE-2016-4456)

Summary:	CVE-2016-4456 gnutls: Environment variable GNUTLS_KEYLOGFILE is obtained via insecure getenv()
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	alonbl, bmcclain, carnil, cfergeau, dblechte, eedri, erik-fedora, lsurette, mgoldboi, michal.skrivanek, mike, mprpic, nmavrogi, rh-spice-bugs, rjones, sardella, srevivo, tmraz, ylavi
Target Milestone:	---	Keywords:	Reopened, Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	gnutls 3.4.13	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-09-13 12:40:42 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:	1343508
Bug Blocks:

Description Adam Mariš 2016-06-07 12:00:20 UTC

It was reported that gnutls 3.4.12 uses an environment variable (GNUTLS_KEYLOGFILE) to write the keys of the running sessions. This variable is obtained insecurely via getenv(), meaning that any set-uid program using gnutls can be used to overwrite any file on the filesystem.

Upstream patch:

https://gitlab.com/gnutls/gnutls/compare/fb2a6baef79f4aadfd95e657fe5a18da20a1410e...86076c9b17b9a32b348cafb8b724f57f7da64d58

External References:

http://gnutls.org/security.html#GNUTLS-SA-2016-1

Comment 1 Adam Mariš 2016-06-07 12:00:39 UTC

Acknowledgments:

Name: Nikos Mavrogiannopoulos (Red Hat)

Comment 2 Adam Mariš 2016-06-07 12:01:01 UTC

Created gnutls tracking bugs for this issue:

Affects: fedora-23 [bug 1343508]

Comment 3 Adam Mariš 2016-06-07 12:01:38 UTC

*** Bug 1343342 has been marked as a duplicate of this bug. ***

Comment 4 Fedora Update System 2016-06-08 22:52:31 UTC

gnutls-3.4.13-1.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 5 Fedora Update System 2016-06-18 18:39:22 UTC

gnutls-3.4.13-1.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.

Comment 6 Tomas Hoger 2018-09-13 07:53:40 UTC

Quoting more detailed description from the upstream advisory:

"""
Setuid programs using GnuTLS 3.4.12 could potentially allow an attacker to overwrite and corrupt arbitrary files in the filesystem. This issue was introduced in GnuTLS 3.4.12 with the GNUTLS_KEYLOGFILE environment variable handling via getenv() and fixed in GnuTLS 3.4.13 by switching to secure_getenv() where available. Recommendation: Upgrade to GnuTLS 3.4.13, or later versions.
"""

https://www.gnutls.org/security.html#GNUTLS-SA-2016-1

Comment 10 Tomas Hoger 2018-09-13 12:40:42 UTC

Note that changes to use secure_getenv() instead of getenv() were also applied to GnuTLS 3.3 in version 3.3.24:

https://gitlab.com/gnutls/gnutls/commit/b0a3048e56611a2deee4976aeba3b8c0740655a6

Those changes are not believed to have any security impact.