IBM AIX Buffer Overflow in ftpd Lets Remote Authenticated Users Execute Arbitrary Code
SecurityTracker Alert ID: 1024368|
SecurityTracker URL: http://securitytracker.com/id/1024368
(Links to External Site)
Updated: Sep 2 2010|
Original Entry Date: Aug 26 2010
Execution of arbitrary code via network, User access via network|
Fix Available: Yes Vendor Confirmed: Yes Exploit Included: Yes |
Version(s): 5.3 and prior versions|
A vulnerability was reported in IBM AIX ftpd. A remote authenticated user can execute arbitrary code on the target system.|
A remote authenticated user can send a specially crafted NLST command to trigger a buffer overflow and execute arbitrary code on the target system.
In some configurations (where FTP allows write access), a remote authenticated user can exploit this flaw to obtain DES-encrypted user hashes.
A demonstration exploit is available at:
Kingcope reported this vulnerability.
A remote authenticated user can execute arbitrary code on the target system.|
The vendor has issued a fix.|
The vendor's advisory is available at:
Vendor URL: aix.software.ibm.com/aix/efixes/security/ftpd_advisory.asc (Links to External Site)
Source Message Contents
Date: Thu, 26 Aug 2010 13:46:57 +0000|
Subject: AIX ftpd
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IBM SECURITY ADVISORY
First Issued: Wed Aug 25 15:51:53 CDT 2010
The most recent version of this document is available here:
VULNERABILITY: AIX ftpd buffer overflow vulnerability
PLATFORMS: AIX 5.3, and earlier releases
SOLUTION: Apply the fix or workaround as described below.
THREAT: A remote attacker may be able to execute arbirary
code on a vulnerable server.
CERT VU Number: n/a
CVE Number: n/a
Reboot required? NO
Protected by FPM? NO
Protected by SED? NO
There is a buffer overflow vulnerability in the ftp server. By
issuing an overly long NLST command, an attacker may cause a
The successful exploitation of this vulnerability allows a remote
attacker to get the DES encrypted user hashes off the server if
FTP is configured to allow write access using Anonymous account
or another account that is available to the attacker.
The following executable is vulnerable:
Please see the following for more information:
II. PLATFORM VULNERABILITY ASSESSMENT
Note: To use the following commands on VIOS you must first
To determine if your system is vulnerable, execute the following
lslpp -L bos.net.tcp.client
The following fileset levels are vulnerable:
AIX Fileset Lower Level Upper Level
bos.net.tcp.client 126.96.36.199 188.8.131.52
bos.net.tcp.client 184.108.40.206 220.127.116.11
bos.net.tcp.client 18.104.22.168 22.214.171.124
bos.net.tcp.client 126.96.36.199 188.8.131.52
Fixes are now available. The fixes can be downloaded from:
The links above are to a tar file containing this signed
advisory, fix packages, and PGP signatures for each package.
AIX Level VIOS Level Fix
To extract the fixes from the tar file:
tar xvf qoslist_fix.tar
Verify you have retrieved the fixes intact:
The checksums below were generated using the "csum -h SHA1"
(sha1sum) commands and are as follows:
csum -h SHA1 (sha1sum) filename
To verify the sums, use the text of this advisory as input to
csum or sha1sum. For example:
csum -h SHA1 -i ftpd_advisory.asc
sha1sum -c ftpd_advisory.asc
These sums should match exactly. The PGP signatures in the tar
file and on this advisory can also be used to verify the
integrity of the fixes. If the sums or signatures cannot be
confirmed, contact IBM AIX Security and describe the
discrepancy at the following addresses:
B. FIX INSTALLATION
IMPORTANT: If possible, it is recommended that a mksysb backup
of the system be created. Verify it is both bootable and
readable before proceeding.
Fix management documentation can be found at:
To preview fix installation:
emgr -e fix_name -p # where fix_name is the name of the
# fix being previewed.
To install fix package:
emgr -e fix_name -X # where fix_name is the name of the
# fix being installed.
IBM has assigned the following APARs to this problem:
AIX Level APAR number Service pack date
5.3.9 IZ83252 tbd
5.3.10 IZ83274 tbd
5.3.11 IZ83275 tbd
5.3.12 IZ83276 tbd
Subscribe to the APARs here:
By subscribing, you will receive periodic email alerting you
to the status of the APAR, and a link to download the service
pack when it becomes available.
Configure ftp daemon to disallow write access to anonymous FTP
users will limit the ability to create a directory that can
trigger this vulnerability.
VI. CONTACT INFORMATION
If you would like to receive AIX Security Advisories via email,
and click on the "My notifications" link.
To view previously issued advisories, please visit:
Comments regarding the content of this announcement can be
To obtain the PGP public key that can be used to communicate
securely with the AIX Security Team you can either:
A. Send an email with "get key" in the subject line to:
B. Download the key from our web page:
C. Download the key from a PGP Public Key Server. The key ID is:
Please contact your local IBM AIX support center for any
eServer is a trademark of International Business Machines
Corporation. IBM, AIX and pSeries are registered trademarks of
International Business Machines Corporation. All other trademarks
are property of their respective holders.
This vulnerability was publicly disclosed by Kingcope.
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