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  • CERT Advisory CA-1993-06 wuarchive ftpd Vulnerability

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Original issue date: April 9, 1993
Last revised: September 19, 1997
Attached copyright statement

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

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 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:

  1. 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 ( 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

  2. 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 ----
    +       anonymous = 0;
            if (!strcasecmp(name, "ftp") || !strcasecmp(name, "anonymous")) {
                    if (checkuser("ftp") || checkuser("anonymous")) {
                            reply(530, "User %s access denied.", name);

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.

Copyright 1993 Carnegie Mellon University.

Revision History
September 19, 1997  Attached Copyright Statement
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