Bug 1346461 (CVE-2016-4989)

Summary:	CVE-2016-4989 setroubleshoot: command injection issues
Product:	[Other] Security Response	Reporter:	Tomas Hoger <thoger>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	lvrabec, mgrepl, mmalik, plautrba, security-response-team, ssekidde
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	setroubleshoot 3.2.27.1, setroubleshoot 3.3.9.1	Doc Type:	If docs needed, set a value
Doc Text:	Shell command injection flaws were found in the way the setroubleshoot executed external commands. A local attacker able to trigger certain SELinux denials could use these flaws to execute arbitrary code with root privileges.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-06-23 10:55:56 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:	1339375, 1339377, 1346462, 1346463, 1348526
Bug Blocks:	1332645

Description Tomas Hoger 2016-06-14 21:41:39 UTC

It was discovered that setroubleshoot executed external commands using subprocess.check_output(), commands.getstatusoutput(), or commands.getoutput() without properly sanitizing untrusted inputs used as command arguments.  These inputs originated from SELinux AVC messages.  A local user could use this flaw to execute arbitrary code as root if they could trigger an SELinux denial using a file with a specially crafted name.

The following cases were identified:

- _set_tpath() in audit_data.py - When executing locate command, it used subprocess.check_output() (new setroubleshoot versions) or commands.getstatusoutput() (older versions) to execute command using shell.  A local user could use this flaw to execute commands with setroubleshootd privileges.

- run_fix() in SetroubleshootFixit.py - This DBus service requires administrative authentication by default.  There are currently no known attacks that can be used by non-administrative users.

Comment 1 Tomas Hoger 2016-06-14 21:41:45 UTC

Acknowledgments:

Name: Red Hat Product Security

Comment 3 Tomas Hoger 2016-06-14 21:43:59 UTC

Note that this issue was independently reported by Sebastian Krahmer (SuSE Security Team).

Comment 4 Tomas Hoger 2016-06-14 21:45:30 UTC

The impact of this issue on Red Hat Enterprise Linux 7.2 and later is reduced, as setroubleshootd does not run with root privileges, but with privileges of a dedicated non-root user setroubleshoot.

The SetroubleshootFixit service runs with root privileges but, as noted in comment 0, there are currently no known attacks against the service.

Comment 5 Tomas Hoger 2016-06-14 21:47:05 UTC

Note that this issue was originally handled as part of the CVE-2016-4445 (bug 1339183), but was later split out because of different fixed-in versions.

Comment 7 Tomas Hoger 2016-06-21 11:28:03 UTC

Public now via:

http://seclists.org/oss-sec/2016/q2/574

Sebastian Krahmer's exploit:

https://github.com/stealth/troubleshooter/blob/master/straight-shooter.c

Comment 8 Tomas Hoger 2016-06-21 11:44:41 UTC

Created setroubleshoot tracking bugs for this issue:

Affects: fedora-all [bug 1348526]

Comment 9 Tomas Hoger 2016-06-21 20:51:23 UTC

Upstream commits:

https://github.com/fedora-selinux/setroubleshoot/commit/e69378d7e82a503534d29c5939fa219341e8f2ad
https://github.com/fedora-selinux/setroubleshoot/commit/dda55aa50db95a25f0d919c3a0d5871827cdc40f

Comment 10 errata-xmlrpc 2016-06-21 21:25:19 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2016:1267 https://access.redhat.com/errata/RHSA-2016:1267

Comment 11 errata-xmlrpc 2016-06-23 08:53:27 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:1293 https://access.redhat.com/errata/RHSA-2016:1293