Majordomo Vulnerabilities

Original issue date: June 9, 1994
Last revised: September 23, 1997
Updated copyright statement

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

The CERT Coordination Center has received reports of vulnerabilities in all versions of Majordomo up to and including version 1.91. These vulnerabilities enable intruders to gain access to the account that runs the Majordomo software, even if the site has firewalls and TCP wrappers.

We recommend that all sites running Majordomo replace their current version with version 1.92 (see Section III for instructions). It is possible to apply a quick fix to versions prior to 1.92, but we strongly recommend obtaining 1.92 instead.

We will update this advisory as we receive additional information. Please check advisory files regularly for updates that relate to your site.

I. Description

Two vulnerabilities have recently been found in Majordomo. These vulnerabilities enable intruders to gain access to the account that runs the Majordomo software, thus gaining the ability to execute arbitrary commands. The vulnerabilities can be exploited without a valid user name and password on the local machine, and firewalls and TCP wrapper protection can be bypassed. The CERT/CC has received reports that the vulnerabilities are currently being exploited.

II. Impact

Intruders can install and execute programs as the user running the Majordomo software.

III. Solution

A. Recommended solution for all versions through 1.92

Obtain and install Majordomo version 1.93.

This version is available from

MD5 (majordomo-1.93.README) = 068bb343f23d3119cd196ed4222ab266
MD5 (majordomo-1.93.tar.Z) = c589a3c3d420d68e096eafdfdac0c8aa

B. Quick fix for versions 1.91 and earlier

Until you are able to install the new version of Majordomo, you should install the following quick fix, which has two steps. If you are running Majordomo 1.90 and earlier, you must take both steps. If you are running version 1.91, you need only take the first step.

Step 1 - Disable new-list by either renaming the new-list program or removing it from the aliases file.

If you have version 1.90 and earlier, go on to Step 2.

Step 2 - In every place in the Majordomo code where there is a string of any of these forms,

"|/usr/lib/sendmail -f<whatever> $to"
"|/usr/lib/sendmail -f<whatever> $reply_to" #request-answer
"|/usr/lib/sendmail -f<whatever> $reply_to $list-approval" # new-list
"|/usr/lib/sendmail -f<whatever> \$to"
Change that string to
"|/usr/lib/sendmail -f<whatever> -t
Generally, you will find the strings in the request-answer file, the file, and your local file.

Note: If you are running a mailer other than sendmail, this step may not fix the vulnerability. You should obtain and install version 1.92 as described in Section A above.

The CERT Coordination Center thanks Brent Chapman of Great Circle Associates and John Rouillard of the University of Massachusetts at Boston for their support in responding to the problem.

Copyright 1994, 1996 Carnegie Mellon University.

Revision History
Sep. 23, 1997  Updated copyright statement
Aug. 30, 1996  Information previously in the README was inserted
               into the advisory. Changed URL format.
June 09, 1995  Sec. III.A - pointer to majordomo 1.93
June 1994      Sec. III.A - Added alternative FTP sites
               Sec. III.B - Revised step 2 of the workaround