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fetchmail-SA-2006-02: TLS enforcement problem/MITM attack/password exposure
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Topics: fetchmail cannot enforce TLS
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Author: Matthias Andree
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Type: secret information disclosure
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Impact: fetchmail can expose cleartext password over unsecure link
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fetchmail may not detect man in the middle attacks
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Credits: Isaac Wilcox (bug report, collaboration on fix)
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CVE Name: CVE-2006-5867
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URL: http://fetchmail.berlios.de/fetchmail-SA-2006-02.txt
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Project URL: http://fetchmail.berlios.de/
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Affects: fetchmail releases <= 6.3.5
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fetchmail release candidate 6.3.6-rc1
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Not affected: fetchmail release candidate 6.3.6-rc2
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fetchmail release 6.3.6
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Corrected: 2006-11-12 fetchmail 6.3.6-rc2
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2006-11-12 internal review draft
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fetchmail is a software package to retrieve mail from remote POP2, POP3,
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IMAP, ETRN or ODMR servers and forward it to local SMTP, LMTP servers or
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message delivery agents.
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fetchmail ships with a graphical, Python/Tkinter based configuration
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utility named "fetchmailconf" to help the user create configuration (run
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control) files for fetchmail.
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2. Problem description and Impact
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=================================
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Fetchmail has no configuration facility to enforce TLS connections.
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Configuring --sslproto 'tls1' does not cause connection aborts if TLS is
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not offered or the TLS handshake fails for POP3 or IMAP.
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Even if fetchmail is forced to validate an TLS certificate by means of
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--sslfingerprint or --sslcertck, it may expose cleartext credentials
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over an unencrypted connection.
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This can cause eavesdroppers to obtain the password without fetchmail's
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Use fetchmail --ssl --sslcertck --sslproto ssl3 (or equivalent in the
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run control file) if your upstream offers SSLv3-wrapped service on a
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Download and install fetchmail 6.3.6 or a newer stable release from
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fetchmail's project site at
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<http://developer.berlios.de/project/showfiles.php?group_id=1824>.
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A. Copyright, License and Warranty
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==================================
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(C) Copyright 2006 by Matthias Andree, <matthias.andree@gmx.de>.
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This work is licensed under the Creative Commons
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Attribution-NonCommercial-NoDerivs German License. To view a copy of
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this license, visit http://creativecommons.org/licenses/by-nc-nd/2.0/de/
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or send a letter to Creative Commons; 559 Nathan Abbott Way;
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Stanford, California 94305; USA.
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THIS WORK IS PROVIDED FREE OF CHARGE AND WITHOUT ANY WARRANTIES.
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Use the information herein at your own risk.
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END OF fetchmail-SA-2006-02.txt