Date: 07 July 2000
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AUSCERT External Security Bulletin Redistribution
ESB-2000.162 -- FreeBSD-SA-00:28.majordomo
majordomo is not safe to run on multi-user machines
7 July 2000
AusCERT Security Bulletin Summary
Vendor: FreeBSD Ports Collection
Operating System: FreeBSD
Impact: Execute Arbitrary Code/Commands
Modify Arbitrary files
Access Required: Local, Existing User
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FreeBSD-SA-00:28 Security Advisory
Topic: majordomo is not safe to run on multi-user machines
Affects: Ports collection.
Corrected: See below
Vendor status: Problem documented
FreeBSD only: NO
Majordomo is a popular mailing-list manager.
II. Problem Description
Majordomo contains a number of perl scripts which are executed by a
setuid wrapper for providing mailing-list management
functionality. However there are numerous weaknesses in these scripts
which allow unprivileged users to run arbitrary commands as the
majordomo user, as well as obtaining read and write access to the
mailing list data.
The majordomo port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 3400 third-party applications in a ready-to-install
FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.
Unprivileged local users can run commands as the 'majordomo' user,
including accessing and modifying mailing-list subscription data.
If you have not chosen to install the majordomo port/package, then
your system is not vulnerable to this problem.
Deinstall the majordomo port/package, if you you have installed it, or
limit the permissions of the majordomo/ directory and/or its contents
appropriately (see below).
Since the vendor has chosen not to fix the various security holes in
the default installation of majordomo, there is no simple solution. It
may be possible to adequately secure the majordomo installation while
retaining required functionality, by tightening the permissions on the
/usr/local/majordomo directory and/or its contents, but these actions
are not taken by the FreeBSD port and are beyond the scope of this
Instead we recommend that majordomo not be used on a system which
contains untrusted users, or an alternative mailing-list manager be
used. There are several such utilities in the FreeBSD ports
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