AUSCERT External Security Bulletin Redistribution
         ESB-2000.105 -- IBM Outside Advisory ERS-OAR-E01-2000:087.1
                       Filesystem vulnerability in AIX
                                 25 May 2000


	AusCERT Security Bulletin Summary

Product:		AIX Filesystem
Vendor:			IBM
Operating System:	AIX 3.2.x
                        AIX 4.1.x
                        AIX 4.2.x
                        AIX 4.3.x
Platform:		N/A

Impact:			Modify Arbitrary files
Access Required:	Local

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                           EMERGENCY RESPONSE SERVICE

19 May 2000 14:30 GMT                          Number:

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                           VULNERABILITY SUMMARY

VULNERABILITY:    Filesystem vulnerability in AIX

PLATFORMS:        IBM AIX(r) versions 3.2.x, 4.1.x, 4.2.x, 4.3.x

SOLUTION:         Apply the fixes listed below.

THREAT:           Non-privileged local users can gain write access
                  to some files.

                           DETAILED INFORMATION

I.  Description

Local users could gain write access to some files on local or remotely
mounted AIX filesystems, even though the file permissions do not allow
write access.  This vulnerability was discovered in the IBM laboratory
during analysis of filesystem behavior and is not exposed during normal
system operation.

II.  Impact

A local user could gain write access to some files on local or remotely
mounted AIX filesystems, even though the file permissions do not allow
write access.

III.  Solutions

  A.  Official fix

      The following fixes can be obtained from the AIX Fix Distribution
      Service at the following URL:


      AIX 3.2.x: APAR IY10111
      AIX 4.1.x: APAR IY10031
      AIX 4.2.x: APAR IY10001
      AIX 4.3.x: APAR IY09941

     In addition, an emergency fix specifically built to install on AIX
     4.3.2 systems is available at the following URL:


IV. Acknowledgements

Thanks to Pat Barrett and Dave Larson for bringing this problem to our

V. Obtaining Fixes

IBM AIX APARs may be ordered using Electronic Fix Distribution (via the
FixDist program), or from the IBM Support Center.  For more information
on FixDist, and to obtain fixes via the Internet, please reference


or send electronic mail to "aixserv@austin.ibm.com" with the word
"FixDist" in the "Subject:" line.  To facilitate ease of ordering all
security related APARs for each AIX release, security fixes are
periodically bundled into a cumulative APAR.  For more information on
these cumulative APARs including last update and list of individual
fixes, send electronic mail to "aixserv@austin.ibm.com" with the word
"subscribe Security_APARs" in the "Subject:" line.

VI.  Contact Information

Comments regarding the content of this announcement can be directed to
your local IBM support center or to:


To request the PGP public key that can be used to encrypt new AIX
security vulnerabilities, send email to security-alert@austin.ibm.com
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IBM and AIX are a registered trademark of International Business
Machines Corporation.  All other trademarks are property of their
respective holders.



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The information in this document is provided as a service to customers of
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