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Home » Security Advisories» FreeBSD » ee temporary file privilege escalation

ee temporary file privilege escalation

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 enable them to overwrite files on the system in the context of the user running the ee editor.

  • Vendor: FreeBSD
  • Vendor ID: SA-06:02.ee
  • Date: January 11, 2006


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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
.

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
- -------------------------------------------------------------------------
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
- -------------------------------------------------------------------------

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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