Bug 1256686 (CVE-2015-5224)

Summary:	CVE-2015-5224 util-linux: File name collision due to incorrect mkstemp use
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jonathan, kzak
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-09-02 12:03:36 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:	1256751
Bug Blocks:	1256689

Description Adam Mariš 2015-08-25 09:27:24 UTC

The following vulnerability in util-linux was announced (taken from http://seclists.org/oss-sec/2015/q3/423):

"""
If the chfn and chsh binaries (both setuid-root) from
util-linux/login-utils are compiled WITHOUT libuser support, they
eventually call mkostemp(localtmp, O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC);
where localtmp is "/etc/%s.XXXXXX" and %s is __progname (i.e., argv[0]'s
basename).

An attacker could repeatedly execve chfn as "ld.so" until mkostemp()
creates "/etc/ld.so.preload" (after a few days, in our tests).  This
particular example doesn't actually work, because "preload" is 7 chars
and "XXXXXX" is 6 chars, but it seems there are other interesting
possibilities, like "/etc/rc.status" and "/etc/krb5.keytab".

The impact of this vulnerability is probably very limited: most Linux
distributions ship either the chfn/chsh binaries from the shadow-utils
(NOT the login-utils ones), or the login-utils ones but WITH libuser
support.
"""

Upstream patch:
https://github.com/karelzak/util-linux/commit/bde91c85bdc77975155058276f99d2e0f5eab5a9

Comment 1 Adam Mariš 2015-08-25 12:02:39 UTC

Created util-linux tracking bugs for this issue:

Affects: fedora-all [bug 1256751]

Comment 2 Stefan Cornelius 2015-09-02 12:03:36 UTC

We're not affected. Our binaries do not use the mkostemp function.


Statement: 

This issue did not affect the versions of util-linux as shipped with Red Hat Enterprise Linux 5 and 7. This issue does not affect the versions of util-linux-ng as shipped with Red Hat Enterprise Linux 6.