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CA-93:06                        CERT Advisory
                                April 9, 1993
                         wuarchive ftpd Vulnerability

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

The CERT Coordination Center has received information concerning a
vulnerability in versions of wuarchive ftpd available before April 8,
1993.  Vulnerable wuarchive ftpd versions were available from
wuarchive.wustl.edu:/packages/ftpd.wuarchive.shar and many other
anonymous FTP sites.

We strongly recommend that any site using versions of wuarchive ftpd 
dating prior to April 8, 1993, immediately take corrective action or 
remove this service.

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

I.   Description

     A vulnerability exists in the access control mechanism in this 
     version of ftpd.
     
II.  Impact

     Anyone (remote or local) can potentially gain access to any 
     account including root on a host running this version of ftpd.

III. Solution 

     Affected sites may choose to disable anonymous FTP service until
     they have corrected this problem.
        
     Affected sites can correct this problem through one of the
     following two procedures:

     A. A new version of ftpd has been released that provides new features
        and also fixes this security problem.  Sites can obtain this new 
        version via anonymous FTP from wuarchive.wustl.edu (128.252.135.4). 
        The files are located in:

                                                      Size      Checksum
        /packages/wuarchive-ftpd/wu-ftpd-2.0.shar    421953      08786
        /packages/wuarchive-ftpd/wu-ftpd-2.0.tar     491520      27466

     B. Make modifications to your existing wuarchive ftpd sources using
        the diff output provided below, recompile and install according to 
        the instructions provided. 

*** ftpd.c.orig
- --- ftpd.c
***************
*** 413,418 ****
- --- 413,420 ----
                end_login();
        }
  
+       anonymous = 0;
+ 
        if (!strcasecmp(name, "ftp") || !strcasecmp(name, "anonymous")) {
                if (checkuser("ftp") || checkuser("anonymous")) {
                        reply(530, "User %s access denied.", name);

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The CERT Coordination Center wishes to thank Scott Paisley, Computer Systems 
Support Manager, Factory Automated Systems Division, N.I.S.T., for informing 
us of this vulnerability.  We would also like to thank Chris Myers, Washington
University, for his quick response to this problem.
- ---------------------------------------------------------------------------

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

Internet E-mail: cert@cert.org
Telephone: 412-268-7090 (24-hour hotline)
           CERT personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4),
           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 for anonymous FTP
from cert.org (192.88.209.5).


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