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Home » Security Advisories» FreeBSD » Cvsbug race condition

Cvsbug race condition

A temporary file is created, used, deleted, and then re-created with the same name. This creates a window during which an attacker could replace the file with a link to another file.

  • Vendor: FreeBSD
  • Vendor ID: SA-05:20.cvsbug
  • Date: September 07, 2005


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===================================================================
FreeBSD-SA-05:20.cvsbug Security Advisory
The FreeBSD Project

Topic: Race condition in cvsbug

Category: contrib
Module: contrib_cvs
Announced: 2005-09-07
Credits: Marcus Meissner
Affects: All FreeBSD releases
Corrected: 2005-09-07 13:43:05 UTC (RELENG_6, 6.0-BETA5)
2005-09-07 13:43:23 UTC (RELENG_5, 5.4-STABLE)
2005-09-07 13:43:36 UTC (RELENG_5_4, 5.4-RELEASE-p7)
2005-09-07 13:43:50 UTC (RELENG_5_3, 5.3-RELEASE-p21)
2005-09-07 13:44:06 UTC (RELENG_4, 4.11-STABLE)
2005-09-07 13:44:20 UTC (RELENG_4_11, 4.11-RELEASE-p12)
2005-09-07 13:44:36 UTC (RELENG_4_10, 4.10-RELEASE-p17)
CVE Name: CAN-2005-2693

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
;.

I. Background

cvsbug(1) is a utility for reporting problems in the CVS revision
control system. It is based on the GNATS send-pr(1) utility.

II. Problem Description

A temporary file is created, used, deleted, and then re-created with
the same name. This creates a window during which an attacker could
replace the file with a link to another file.

While cvsbug(1) is based on the send-pr(1) utility, this problem does
not exist in the version of send-pr(1) distributed with FreeBSD.

III. Impact

A local attacker could cause data to be written to any file to which
the user running cvsbug(1) has write access. This may cause damage in
itself (e.g., by destroying important system files or documents) or may
be used to obtain elevated privileges.

IV. Workaround

Do not use the cvsbug(1) utility on any system with untrusted users.

V. Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
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 patch has been verified to apply to FreeBSD 4.10, 4.11,
5.3, and 5.4 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-05:20/cvsbug.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/gnu/usr.bin/cvs/cvsbug
# 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
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.4
RELENG_4_11
src/UPDATING 1.73.2.91.2.13
src/sys/conf/newvers.sh 1.44.2.39.2.16
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.3.2.1
RELENG_4_10
src/UPDATING 1.73.2.90.2.18
src/sys/conf/newvers.sh 1.44.2.34.2.19
src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.2.6.1
RELENG_5
src/contrib/cvs/src/cvsbug.in 1.1.1.3.2.1
RELENG_5_4
src/UPDATING 1.342.2.24.2.16
src/sys/conf/newvers.sh 1.62.2.18.2.12
src/contrib/cvs/src/cvsbug.in 1.1.1.3.6.1
RELENG_5_3
src/UPDATING 1.342.2.13.2.24
src/sys/conf/newvers.sh 1.62.2.15.2.26
src/contrib/cvs/src/cvsbug.in 1.1.1.3.4.1
RELENG_6
src/contrib/cvs/src/cvsbug.in 1.1.1.3.8.1
- -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2693

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:20.cvsbug.asc
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