Operating System:

Published:

15 August 2002

Protect yourself against future threats.

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                   ESB-2002.443 -- IBM SECURITY ADVISORY
            Vulnerabilities in CDE ToolTalk RPC Database Server
                              16 August 2002

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:                CDE ToolTalk RPC Database Server
Operating System:       AIX 4.3
                        AIX 5.1
Impact:                 Root Compromise
                        Execute Arbitrary Code/Commands
                        Denial of Service
Access Required:        Remote

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IBM SECURITY ADVISORY

Initial Release: Mon Aug 12 16:35:38 CDT 2002

===========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:    Vulnerabilities in CDE ToolTalk RPC Database Server

PLATFORMS:        IBM AIX 4.3 and 5.1

SOLUTION:         Apply the emergency-fixes described below

THREAT:           Malicious remote user can cause denial of service,
                  possibly execute arbitrary code.

CERT Advisory:    CA-2002-26 
CERT VU Number:   VU#387387   
CVE  Number:      CAN-2002-0679

===========================================================================
                           DETAILED INFORMATION

I.  Description

   This advisory addresses a vulnerability in the CDE ToolTalk RPC database
   server. This vulnerability is summarized below. Further details can be
   found in the CERT advisory and vulnerability notes.

   The ToolTalk RPC database server is a component of the CDE desktop and
   allows applications to communicate with each other via RPC calls between
   different machines and platforms. The RPC database server manages connections
   between these ToolTalk applications. This component is vulnerable to a 
   buffer overflow condition via the _TT_CREATE_FILE() function. By using a 
   specially crafted RPC message, an attacker could cause a denial of service 
   condition or possibly execute arbitrary code.


II. Impact

   A malicious remote user can use this vulnerability in combination with
   other techniques to execute arbitrary code. Since the server usually runs as
   root, this can enable a remote attacker to gain root privileges and/or
   cause a denial of service condition on the machine.


III.  Solutions

  A.  Official fix

      AIX 4.3:  APAR #IY32792
      AIX 5.1:  APAR #IY32793

      NOTE: Fix will not be provided for versions prior to 4.3 as
      these are no longer supported by IBM. Affected customers are
      urged to upgrade to 4.3.3 at the latest maintenance level,
      or to 5.1.


  B.  How to minimize the vulnerability


    WORKAROUND

    The only workaround currently it to disable the CDE Tooltalk RPC database server
    and kill any running rpc.ttdbserver processes.

    This can be accomplished on AIX by first commenting-out the rpc.ttdbserver entry in
    the /etc/inetd.conf file using the "#" character.

    #ttdbserver      sunrpc_tcp      tcp     wait    root    /usr/dt/bin/rpc.ttdbserver

    Then send the inetd process a HUP signal to re-read inetd.conf using the following
    commands:

    # ps -ef | grep -v grep | grep inetd     # to get inetd-pid 
    # kill -HUP inetd-pid                    # send HUP signal to inetd

    Any currently running rpc.ttdbserver processes must also be killed. This
    can be done as follows:

    # ps -ef | grep -v grep | grep ttdbserver         # to get ttdbserver pid 
    # kill -HUP ttdbserver-pid                        # kill ttdbserver process

    Note: If you choose to disable ttdbserver, be sure re-enable it after installing
    the efix or APAR.


    EMERGENCY FIX (efix):


    Download the efix:
    ------------------
    Temporary fixes for AIX 4.3.3 and 5.1 systems are available.

    The temporary fixes can be downloaded via ftp from:

    ftp://aix.software.ibm.com/aix/efixes/security

    The name of the efix you want to download to close this vulnerability is
    ttdbserver_3_efix.tar.Z.


    Unpack and Verify the efix:
    ---------------------------
    Move the efix package to a temporary directory and unpack it using the 
    following commands:

       # uncompress ttdbserver_3_efix.tar.Z
       # tar -xvf ttdbserver_3_efix.tar

    This package contains a PGP-signed advisory and tarfiles of the patched
    rpc.ttdbserver binaries for AIX 4.3.3 and AIX 5.1.0. Detached PGP signatures
    are also provided for the tarfiles. The checksums for the tarfiles were
    generated using the "sum" and "md5" commands and are as follows:

    Filename                       sum                  md5
    ==========================================================================
    rpc.ttdbserver.433.tar      56609   350   101a82994e0ac438e4a7d6156d7ce47c
    rpc.ttdbserver.510.tar      33997   340   8bb06eaab06646e2c589d57f5e7241ce

    These sums should match exactly; if they do not, double check the hash
    results and the download site address. If OK, contact IBM AIX Security
    at security-alert@austin.ibm.com and describe the discrepancy.



    efix Installation Instructions:
    -------------------------------

   1. Become root, if not already done.

   2. Untar the tar file for your AIX release into a temporary directory.
      This will create a directory tree under the temporary directory 
      containing the executable. In this case, "usr/dt/bin".

   3. To replace rpc.ttdbserver use the following commands:


      # cd /usr/dt/bin
      # mv rpc.ttdbserver rpc.ttdbserver.orig    # make a backup copy!
      # mv /tmp/usr/dt/bin/rpc.ttdbserver.xx .   # "xx" = 433 or 510
      # mv rpc.ttdbserver.xx rpc.ttdbserver      # "xx" = 433 or 510
      # chmod 555 rpc.ttdbserver
      # chown bin:bin rpc.ttdbserver
      # slibclean

      Finally, exit the CDE and re-login.



IV. 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

        http://techsupport.services.ibm.com/rs6k/fixes.html

or send email 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 email to "aixserv@austin.ibm.com" with
the word "subscribe Security_APARs" in the "Subject:" line.


V.  Acknowledgments

Thanks to Sinan Eren of Entercept Technologies for identifying this
vulnerability in CDE ToolTalk and to CERT for notifying us regarding
these security issues.


VI.  Contact Information

Comments regarding the content of this announcement can be directed to:

   security-alert@austin.ibm.com

To request the PGP public key that can be used to encrypt new AIX
security vulnerabilities, send email to security-alert@austin.ibm.com
with a subject of "get key".

If you would like to subscribe to the AIX security newsletter, send a
note to aixserv@austin.ibm.com with a subject of "subscribe Security".
To cancel your subscription, use a subject of "unsubscribe Security".
To see a list of other available subscriptions, use a subject of
"help".

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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