Bug 1256686 - (CVE-2015-5224) CVE-2015-5224 util-linux: File name collision due to incorrect mkstemp use
CVE-2015-5224 util-linux: File name collision due to incorrect mkstemp use
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
low Severity low
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Assigned To: Red Hat Product Security
: Security
Depends On: 1256751
Blocks: 1256689
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Reported: 2015-08-25 05:27 EDT by Adam Mariš
Modified: 2015-09-02 08:03 EDT (History)
2 users (show)

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Doc Type: Bug Fix
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Last Closed: 2015-09-02 08:03:36 EDT
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Description Adam Mariš 2015-08-25 05:27:24 EDT
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

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

Upstream patch:
Comment 1 Adam Mariš 2015-08-25 08:02:39 EDT
Created util-linux tracking bugs for this issue:

Affects: fedora-all [bug 1256751]
Comment 2 Stefan Cornelius 2015-09-02 08:03:36 EDT
We're not affected. Our binaries do not use the mkostemp function.


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.

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