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Security Advisory                                                       CERT-NL
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Author/Source : CERT-NL (Don Stikvoort )                    Index  :    S-94-08
Distribution  : World                                       Page   :          1
Classification: External                                    Version:      Final
Subject       : wuarchive ftpd Trojan Horse                 Date   :  07-Apr-94
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CERT-NL received information on SOURCES of the popular wuarchive FTP daemon
(ftpd) containing a Trojan horse.

If you're running wuarchive ftpd please read this advisory and take the
appropriate action! 
  
All honours to CERT/CC as provider of the following information:
 
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The CERT Coordination Center has received confirmation that some copies
of the source code for the wuarchive FTP daemon (ftpd) were modified by 
an intruder, and contain a Trojan horse.

We strongly recommend that any site running the wuarchive ftpd take steps 
to immediately install version 2.3, or disable their FTP daemon.

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I.   Description

     Some copies of the source code for versions 2.2 and 2.1f of the 
     wuarchive ftpd were modified by an intruder, and contain a Trojan
     horse.  If your FTP daemon was compiled from the intruder-modified 
     source code, you are vulnerable.

     It is possible that previous versions of the source code for the server 
     were modified in a similar manner.

     If you are running the wuarchive ftpd, but not providing anonymous FTP 
     access, you are still vulnerable to this Trojan horse.


II.  Impact

     An intruder can gain root access on a host running an FTP daemon 
     that contains this Trojan horse.


III. Solution

     We strongly recommend that any site running the wuarchive ftpd (version 
     2.2 or earlier) take steps to immediately install version 2.3. 

     If you cannot install the new version in a timely manner, you should 
     disable FTP service.  It is not sufficient to disable anonymous FTP.  
     You must disable the FTP daemon. 

     Sites can obtain version 2.3 via anonymous FTP from ftp.uu.net, in the 
     "/networking/ftp/wuarchive-ftpd" directory.  We recommend that you turn
     off your FTP server until you have installed the new version.  

     Be certain to verify the checksum information to confirm that you have
     retrieved a valid copy.

                        BSD        SVR4         
     File               Checksum   Checksum    MD5 Digital Signature
     -----------------  --------   ---------   --------------------------------
     wu-ftpd-2.3.tar.Z  24416 181  30488 361   e58adc5ce0b6eae34f3f2389e9dc9197


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The CERT Coordination Center wishes to thank Bryan O'Connor and Chris Myers 
of Washington University in St. Louis for their invaluable assistance in 
resolving this problem.  CERT also gratefully acknowledges the help of
Neil Woods and Karl Strickland.
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CERT-NL is the Computer Emergency Response Team, located in The
Netherlands. CERT-NL is a Full Member of the Forum of Incident Response
and Security Teams (FIRST). The constituency of CERT-NL are the SURFnet
connected institutions.
 
Past CERT-NL Security Bulletins and other CERT-NL related material can
be found on the anonymous FTP server of SURFnet bv:
"ftp.nic.surfnet.nl" [192.87.46.3], in the directory
"surfnet/net-security/cert-nl/docs/bulletin".  This information is also
available using email. Send an email saying "help" to
"mailserv@nic.surfnet.nl".
 
In case of computer or network security problems please contact CERT-NL
or the CERT of your own constituency. Please be aware of the fact that
we are one (when DST is in effect two) hour(s) ahead of Universal Time
Coordinated (i.e. UTC+0100 (UTC+0200)).
Email:     cert-nl@surfnet.nl
Phone:     +31 30 310290
Fax:       +31 30 340903
Snailmail: SURFnet bv
           Attn. CERT-NL
           P.O. Box 19035
           NL - 3501 DA  UTRECHT
           The Netherlands
A 7 * 24 hours phone number is available to SURFnet SSC's and FIRST
members on request.
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