=============================================================================
CA-94:07                         CERT Advisory
                                 April 6, 1994
                          wuarchive ftpd Trojan Horse
-----------------------------------------------------------------------------

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.

-----------------------------------------------------------------------------

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


---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------

If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in the Forum of Incident
Response and Security Teams (FIRST).

If you wish to send sensitive incident or vulnerability information to 
CERT via electronic mail, CERT strongly advises that the e-mail be encrypted.
CERT can support a shared DES key, PGP (public key available via
anonymous FTP on info.cert.org), or PEM (contact CERT for details).

Internet E-mail: cert@cert.org
Telephone: 412-268-7090 (24-hour hotline)
           CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4),
           and are on call for emergencies during other hours.

CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890

Past advisories, information about FIRST representatives, and other
information related to computer security are available via anonymous
FTP from info.cert.org.