Original issue date: April 6, 1994<BR>
Last revised: September 23, 1997<BR>
Updated copyright statement

<P>A complete revision history is at the end of this file.

<P>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.

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

<P><HR>
<H2>I. Description</H2>

<P>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.

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

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

<H2>II. Impact</H2>

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

<H2>III. Solution</H2>

<P>We strongly recommend that any site running the wuarchive ftpd
(version 2.2 or earlier) take steps to install the current version.

<P>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.

<P>Sites can obtain version 2.4 via anonymous FTP from

<P>
<A HREF=ftp://ftp.uu.net/networking/ftp/wuarchive-ftpd>ftp://ftp.uu.net/networking/ftp/wuarchive-ftpd</A>

<P>We recommend that you turn off your FTP server until you have
installed the new version.

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

<PRE>
        CHECKSUMS
        System V sum
        ============
        51092    16  patch_2.3-2.4.Z
        20337   362  wu-ftpd-2.4.tar.Z
 
        Berkeley sum
        ============
        09291     8  patch_2.3-2.4.Z
        38213   181  wu-ftpd-2.4.tar.Z
 
        md5 checksum
        ============
        MD5 (patch_2.3-2.4.Z)   = 5558a04d9da7cdb1113b158aff89be8f
        MD5 (wu-ftpd-2.4.tar.Z) = cdcb237b71082fa23706429134d8c32e
 </PRE>

<P><HR>

<P>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.

<P><HR>

<P>
<H2>UPDATES</H2>
Added April 7, 1994

<P>The Trojan horse described in CA-94.07 provides a back-door password
for any username other than &quot;anonymous.&quot; It would be trivial for an
intruder to modify the back-door password or other details of the
Trojan horse code.  The &quot;diff&quot; described in #1 below will help you
detect only the Trojan horse referenced in the advisory.  It will
not detect any other Trojan horses.

<P>Clarifications:

<P>1) If you have modified any version of the wuarchive ftpd and cannot
install the new version, 2.3, you may detect the existence of the
discovered Trojan horse with the following diff on ftpd.c:
<PRE>

1013,1015c1013,1014
&lt;         if ((pw == NULL || *pw->pw_passwd == '\0' ||
&lt;             strcmp(xpasswd, pw->pw_passwd)) &&
&lt;             (strcmp(passwd, "NULL"))) {
- ---
&lt;         if (pw == NULL || *pw->pw_passwd == '\0' ||
&lt;             strcmp(xpasswd, pw->pw_passwd)) {

</PRE>

<P>2) Since the versions containing the Trojan horse were found in a
number of locations, it is possible that your version of the wuarchive
ftpd software contains the Trojan horse regardless of the distribution
site from which you obtained the source code.

<P>3) If you have any questions concerning the wuarchive ftpd software,
send mail to:

<P>Bryan D. O'Connor<BR>
Office of the Network Coordinator<BR>
<A HREF=mailto:bryan@fegmania.wustl.edu>bryan@fegmania.wustl.edu</A> 

Washington University in Saint Louis<BR>
<A HREF=http://fegmania.wustl.edu/~bryan>http://fegmania.wustl.edu/~bryan</A>

<P><HR>

<!--#include virtual="/include/footer_nocopyright.html" -->
<P>Copyright 1994, 1995, 1996 Carnegie Mellon University.</P>

<HR>

Revision History
<PRE>
Sep. 23, 1997  Updated copyright statement
Aug. 30, 1996  Information previously in the README was inserted
               into the advisory.
Feb. 02, 1995  Sec. III - Inserted a pointer and checksums for wu-ftpd-2.4.
Apr. 07, 1994  Updates - Added clarifications and additional assistance.
</PRE>