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AUSCERT External Security Bulletin Redistribution
ESB-2006.0035 -- [UNIX/Linux][FreeBSD]
ee temporary file privilege escalation
12 January 2006
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AusCERT Security Bulletin Summary
---------------------------------
Product: ee
Publisher: FreeBSD
Operating System: FreeBSD
UNIX variants (UNIX, Linux, OSX)
Impact: Overwrite Arbitrary Files
Access: Existing Account
CVE Names: CVE-2006-0055
Original Bulletin:
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:02.ee.asc
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FreeBSD-SA-06:02.ee Security Advisory
The FreeBSD Project
Topic: ee temporary file privilege escalation
Category: core
Module: ee
Announced: 2006-01-11
Credits: Christian S.J. Peron
Affects: All FreeBSD versions
Corrected: 2006-01-11 08:02:16 UTC (RELENG_6, 6.0-STABLE)
2006-01-11 08:03:18 UTC (RELENG_6_0, 6.0-RELEASE-p2)
2006-01-11 08:03:55 UTC (RELENG_5, 5.4-STABLE)
2006-01-11 08:04:33 UTC (RELENG_5_4, 5.4-RELEASE-p9)
2006-01-11 08:05:54 UTC (RELENG_5_3, 5.3-RELEASE-p24)
2006-01-11 08:06:47 UTC (RELENG_4, 4.11-STABLE)
2006-01-11 08:07:18 UTC (RELENG_4_11, 4.11-RELEASE-p14)
2006-01-11 08:08:08 UTC (RELENG_4_10, 4.10-RELEASE-p20)
CVE Name: CVE-2006-0055
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.
I. Background
The ee utility is a simple screen oriented text editor. This editor is
popular with a lot of users due to its ease of use.
II. Problem Description
The ispell_op function used by ee(1) while executing spell check
operations employs an insecure method of temporary file generation.
This method produces predictable file names based on the process ID
and fails to confirm which path will be over written with the user.
It should be noted that ispell does not have to be installed in order
for this to be exploited. The option simply needs to be selected.
III. Impact
These predictable temporary file names are problematic because they
allow an attacker to take advantage of a race condition in order to
execute a symlink attack, which could allow them to overwrite files
on the system in the context of the user running the ee(1) editor.
IV. Workaround
Instead of invoking ispell through ee(1), invoke it directly.
V. Solution
Perform one of the following:
1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE,
or to the RELENG_6_0, RELENG_5_4, RELENG_5_3, RELENG_4_11, or
RELENG_4_10 security branch dated after the correction date.
2) To patch your present system:
The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, 5.4, and 6.0 systems.
a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:02/ee.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:02/ee.patch.asc
b) Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/usr.bin/ee
# make obj && make depend && make && make install
VI. Correction details
The following list contains the revision numbers of each file that was
corrected in FreeBSD.
Branch Revision
Path
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RELENG_4
usr.bin/ee/ee.c 1.16.2.9
RELENG_4_11
src/UPDATING 1.73.2.91.2.15
src/sys/conf/newvers.sh 1.44.2.39.2.18
usr.bin/ee/ee.c 1.16.2.7.6.1
RELENG_4_10
src/UPDATING 1.73.2.90.2.21
src/sys/conf/newvers.sh 1.44.2.34.2.22
usr.bin/ee/ee.c 1.16.2.7.4.1
RELENG_5
usr.bin/ee/ee.c 1.31.4.2
RELENG_5_4
src/UPDATING 1.342.2.24.2.18
src/sys/conf/newvers.sh 1.62.2.18.2.14
usr.bin/ee/ee.c 1.31.4.1.2.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.27
src/sys/conf/newvers.sh 1.62.2.15.2.29
usr.bin/ee/ee.c 1.31.6.1
RELENG_6
usr.bin/ee/ee.c 1.32.2.1
RELENG_6_0
src/UPDATING 1.416.2.3.2.7
src/sys/conf/newvers.sh 1.69.2.8.2.3
usr.bin/ee/ee.c 1.32.4.1
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VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0055
The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:02.ee.asc
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