NSFOCUS SA2006-03 : IBM AIX rm_mlcache_file Local Race Condition Vulnerability

[NSFOCUS Security Team]

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NSFOCUS Security Advisory (SA2006-03)

IBM AIX rm_mlcache_file Local Race Condition Vulnerability=20

Release Date: 2006-04-24

CVE ID: CVE-2006-1247

http://www.nsfocus.com/english/homepage/research/0603.htm

Affected systems & software
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IBM AIX 5.1
IBM AIX 5.2
IBM AIX 5.3

Unaffected systems & software
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Summary
=3D=3D=3D=3D=3D=3D=3D=3D=3D

NSFocus Security Team discovered a local race condition in IBM AIX rm_mlcac=
he_file=20
which could allow a local user to overwrite arbitrary file.

Description
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

rm_mlcache_file shipped with IBM AIX is used to delete some cached files.=20
By default it is set with suid root bit.=20

rm_mlcache_file contains a race condition when processing temporary files w=
hich=20
allows a local attacker to overwrite arbitrary files. Attackers can launch=
=20
attacks by running the program directly, or waiting till root user runs it.
Successful exploitation may result in data loss or DoS, specifically depend=
ing
on the overwritten file.

Workaround
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Remove the execution bit from rm_mlcache_file temporarily:

# chmod 000 /usr/bin/rm_mlcache_file
=20
Vendor Status
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The vendor has released the following APAR patches to fix the vulnerability:

APAR number for AIX 5.1.0: IY82866=20
APAR number for AIX 5.2.0: IY82285
APAR number for AIX 5.3.0: IY82357
=20
AIX 5 APAR patch can be downloaded at:=20
http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html

The temporary patch for the vulnerability can be downloaded at:
ftp://aix.software.ibm.com/aix/efixes/security/rm_mlcache_file_ifix.tar.Z

Additional Information
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The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-1247 to this issue. This is a candidate for inclusion in the=
=20
CVE list (http://cve.mitre.org), which standardizes names for security prob=
lems.
Candidates may change significantly before they become official CVE entries.

Acknowledgment
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Yang Jilong of NSFocus Security Team found the vulnerability.

DISCLAIMS
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NSFOCUS Security Team <security@nsfocus.com>
NSFOCUS INFORMATION TECHNOLOGY CO.,LTD
(http://www.nsfocus.com)

PGP Key: http://www.nsfocus.com/homepage/research/pgpkey.asc
Key fingerprint =3D F8F2 F5D1 EF74 E08C 02FE 1B90 D7BF 7877 C6A6 F6DA


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