IRIX FTP Bounce vulnerability

[SGI Security Coordinator <agent99 () sgi com>]

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______________________________________________________________________________

                          SGI Security Advisory

        Title:      IRIX FTP Bounce vulnerability
        Number:     20020305-01-I
        Date:       March 28, 2002
        Reference:  CERT CA-1997-27
______________________________________________________________________________

SGI provides this information freely to the SGI user community for its
consideration, interpretation, implementation and use.   SGI recommends
that this information be acted upon as soon as possible.

SGI provides the information in this Security Advisory on an "AS-IS" basis
only, and disclaims all warranties with respect thereto, express, implied
or otherwise, including, without limitation, any warranty of merchantability
or fitness for a particular purpose.  In no event shall SGI be liable for
any loss of profits, loss of business, loss of data or for any indirect,
special, exemplary, incidental or consequential damages of any kind arising
from your use of, failure to use or improper use of any of the instructions
or information in this Security Advisory.
______________________________________________________________________________

- -----------------------
- --- Issue Specifics ---
- -----------------------

The IRIX ftpd server daemon can be used as a relay to portscan networks.
The PORT command, part of the FTP protocol, can be used to establish
connections to remote machines other than the FTP client.  While this
is functionality that complies with the FTP RFC, it leads to exposure
to security risks.  This is known as the "FTP bounce" vulnerability.

SGI has investigated this issues and recommends the following
steps for neutralizing the exposure.  It is HIGHLY RECOMMENDED
that these measures be implemented on ALL vulnerable SGI systems.

- --------------
- --- Impact ---
- --------------

An attacker may be able to scan networks that they wouldn't otherwise
have access to.  An attacker may be able to conceal the true origin of
a portscanning attempt.

CERT reported this vulnerability:
http://www.cert.org/advisories/CA-1997-27.html

This vulnerability has been publicly discussed in Usenet
newsgroups and security mailing lists.


- ----------------
- --- Solution ---
- ----------------

With IRIX 6.5.6 or better, one can run the ftpd daemon with the -p
option to prevent this vulnerability:

1) Become the root user on the system.

   % /bin/su -
   Password:
   #

2) Edit the file /etc/inetd.conf with your favorite text editor.

   # vi /etc/inetd.conf

   {Find the following line}

   ftp     stream  tcp     nowait  root    /usr/etc/ftpd   ftpd -l

   {Add the -p option}

   ftp     stream  tcp     nowait  root    /usr/etc/ftpd   ftpd -lp

   {Save the file}

3) Force inetd to re-read the configuration file.

   # /etc/killall -HUP inetd

4) Kill any existing ftpd process.

   # /etc/killall telnetd

5) Return to previous level.

   # exit
   %

- -------------
- --- Links ---
- -------------

SGI Security Advisories can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/advisories/

SGI Security Patches can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/patches/

SGI patches for IRIX can be found at the following patch servers:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/

SGI freeware updates for IRIX can be found at:
http://freeware.sgi.com/

SGI fixes for SGI open sourced code can be found on:
http://oss.sgi.com/projects/

SGI patches and RPMs for Linux can be found at:
http://support.sgi.com/linux/ or
http://oss.sgi.com/projects/sgilinux-combined/download/security-fixes/

SGI patches for Windows NT or 2000 can be found at:
http://support.sgi.com/nt/

IRIX 5.2-6.4 Recommended/Required Patch Sets can be found at:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/support/patchset/

IRIX 6.5 Maintenance Release Streams can be found at:
http://support.sgi.com/colls/patches/tools/relstream/index.html

IRIX 6.5 Software Update CDs can be obtained from:
http://support.sgi.com/irix/swupdates/

The primary SGI anonymous FTP site for security advisories and patches
is patches.sgi.com (216.32.174.211).  Security advisories and patches
are located under the URL ftp://patches.sgi.com/support/free/security/

For security and patch management reasons, ftp.sgi.com (mirrors
patches.sgi.com security FTP repository) lags behind and does not
do a real-time update.


- ------------------------
- --- Acknowledgments ----
- ------------------------

SGI wishes to thank CERT, NASA, and the users of the Internet
Community at large for their assistance in this matter.


- -----------------------------------------
- --- SGI Security Information/Contacts ---
- -----------------------------------------

If there are questions about this document, email can be sent to
security-info () sgi com.

                      ------oOo------

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                      ------oOo------

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                      ------oOo------

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______________________________________________________________________________
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