AIX Anonymous FTP Vulnerability

Original issue date: April 27, 1992
Last revised: September 19, 1997
Attached copyright statement

A complete revision history is at the end of this file.

The Computer Emergency Response Team/Coordination Center (CERT/CC) has received information concerning a vulnerability in the anonymous FTP configuration in all versions of AIX.

IBM is aware of this problem and a fix is available as apar number "ix23944".  This patch is available for all AIX releases from "GOLD".

IBM customers may call IBM Support (800-237-5511) and ask that the fix be shipped to them.  Patches may be obtained outside the U.S. by contacting your local IBM representative.  The fix will appear in the upcoming 2009 update and the next release of AIX.

I. Description

Previous versions of the anonymous FTP installation script, /usr/lpp/tcpip/samples/anon.ftp, incorrectly configured various files and directories.

II. Impact

Remote users can execute unauthorized commands and gain access to the system if anonymous FTP has been installed.

III. Solution

A.  Obtain the fix from IBM Support.

The fix contains three files:

    a "readme" file (README.a23944),
    the fix installation script (install.a23944),
    and an archive containing the updated files (PATCH.a23944.Z).

B.  Install the fix following the instructions in the README file.

The CERT/CC would like to thank Charles McGuire of the Computer Science Department, the University of Montana for bringing this security vulnerability to our attention and IBM for their response to the problem.

This document is available from:

CERT/CC Contact Information

Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890

CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email.  Our public PGP key is available from

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.

Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement.

Conditions for use, disclaimers, and sponsorship information

Copyright 1992 Carnegie Mellon University.

Revision History
September 19,1997  Attached copyright statement