Bug 1181167 (CVE-2015-5700, CVE-2015-5701)

Summary: CVE-2015-5700 CVE-2015-5701 texlive: insecure use of /tmp in mktexlsr
Product: [Other] Security Response Reporter: Vasyl Kaigorodov <vkaigoro>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: novyjindrich, than
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: impact=low,public=20150111,reported=20150112,source=debian,cvss2=2.1/AV:L/AC:L/Au:N/C:N/I:P/A:N,cwe=CWE-377,fedora-all/texlive=affected,rhel-6/texlive=notaffected,rhel-7/texlive=wontfix
Fixed In Version: Doc Type: Bug Fix
Doc Text:
It was discovered that the mktexlsr script of the texlive package creates temporary files in an insecure way. A local attacker could possibly use this flaw to perform a symbolic link attack and overwrite arbitrary files with the privileges of the user running mktexslr, or obtain sensitive information from the temporary files.
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-09-23 11:07:16 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 1181169    
Bug Blocks: 1225847    
Attachments:
Description Flags
mktexlsr.patch none

Description Vasyl Kaigorodov 2015-01-12 14:11:20 UTC
It was reported [1] that mktexlsr script uses /tmp in an insecure way.
Part of original report:
...
This is how mktexlsr uses temporary files (with boring parts snipped):

treefile="${TMPDIR-/tmp}/mktexlsrtrees$$.tmp"
# ...
while test $# -gt 0; do
   # ...
   (umask 077
   if echo "$1" >>"$treefile"; then :; else
     echo "$progname: $treefile: could not append to arg file, goodbye." >&2
     exit 1
   fi
   # ...
done


This is insecure because the filename is predictable and, more 
importantly, the program doesn't fail atomically if the file already 
exists.
...

Suggested patch is attached.

[1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775139

Comment 1 Vasyl Kaigorodov 2015-01-12 14:12:36 UTC
Created attachment 979176 [details]
mktexlsr.patch

Comment 2 Vasyl Kaigorodov 2015-01-12 14:13:02 UTC
Created texlive tracking bugs for this issue:

Affects: fedora-all [bug 1181169]

Comment 3 Ngo Than 2015-04-01 13:16:45 UTC
do we have CVE id for this bug?

Comment 4 Fedora Update System 2015-05-10 23:38:05 UTC
texlive-2014-8.20140525_r34255.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 5 Fedora Update System 2015-05-12 20:38:02 UTC
texlive-2014-7.1.20140525_r34255.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 6 Vasyl Kaigorodov 2015-07-28 15:00:34 UTC
(In reply to Ngo Than from comment #3)
> do we have CVE id for this bug?

Have just requested one on oss-security. This BZ will be updated with the CVE ID once it's assigned.
This is how upstream fixed it:

--- texlive-bin.orig/texk/kpathsea/mktexlsr
+++ texlive-bin/texk/kpathsea/mktexlsr
@@ -73,7 +73,7 @@
 dry_run=false
 trees=

-treefile="${TMPDIR-/tmp}/mktexlsrtrees$$.tmp"
+treefile=`mktemp --tmpdir mktexlsrtrees.XXXXXXXXXX` || exit 1

Comment 7 Martin Prpič 2015-07-30 14:47:28 UTC
MITRE assigned two CVEs, details here:

http://seclists.org/oss-sec/2015/q3/250

Comment 8 Vasyl Kaigorodov 2015-08-04 14:11:36 UTC
To clear things up.

CVE-2015-5700 is for the issue introduced by this commit (lines 69-72):
http://tug.org/svn/texlive/trunk/Build/source/texk/kpathsea/mktexlsr?r1=19613&r2=22885

It looks like later at some point this was fixed to use "mktemp --tmpdir" (commit unknown), and CVE-2015-5701 was assigned to the issue introduced by this commit:
http://tug.org/svn/texlive/trunk/Build/source/texk/kpathsea/mktexlsr?r1=36626&r2=36855

Comment 9 Stefan Cornelius 2015-08-06 13:05:53 UTC
Looks like this was introduced via:
http://tug.org/svn/texlive/trunk/Build/source/texk/kpathsea/mktexlsr?r1=19613&r2=22885

Texlive for RHEL6 does not have this change yet and is not vulnerable.
Texlive for RHEL7, however, ships with this change and is vulnerable.