Full Disclosure mailing list archives
Re: Mutt: failure to check server certificate in SMTP TLS connection
From: Joachim Schipper <joachim () joachimschipper nl>
Date: Tue, 8 Mar 2011 09:00:05 +0100
On Tue, Mar 08, 2011 at 12:36:01PM +1100, dave b wrote:
Hi all. It seems that mutt fails to check the validity of a SMTP servers certificate during a TLS connection. In my mutt configuration I have set ssl_starttls = yes set ssl_force_tls = yes However, after performing the steps below I found that mutt did not properly validate the remote servers SMTP tls certificate. This means that an attacker could potentially MITM a mutt user connecting to their SMTP server even when the user has forced a TLS connection. Steps to test this: 1. I set in my hosts file the ip for smtp.gmail.com to be bound to mail.lolok.com in /etc/hosts 74.125.127.109 mail.LOLOK.com 2.Then I changed my set smtp_url = "smtp://MYUSERNAME () smtp gmail com:587/" to be set smtp_url = "smtp://MYUSERNAME () mail lolok com:587/" 3. I opened up mutt and emailed my self. I note that I saw mutt say "connecting to mail.lolok.com". I feel that this is an issue because mutt _does_ actually perform IMAP server certificate validation (at least it did when I last tested it :P).
I'm on the train and not able to test, but the muttrc(5) man page has smtp_url Type: string Default: "" Defines the SMTP smarthost where sent messages should relayed for delivery. This should take the form of an SMTP URL, e.g.: smtp[s]://[user[:pass]@]host[:port] where "[...]" denotes an optional part. Setting this variable overrides the value of the $sendmail variable. Note the "[s]". But yes, you should arguably file a documentation-bug with the Mutt maintainers, since ssl_starttls does suggest that it works for SMTP too. Joachim _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Current thread:
- Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 07)
- Re: Mutt: failure to check server certificate in SMTP TLS connection Joachim Schipper (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection Tim (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection Tim (Mar 08)
- Re: Mutt: failure to check server certificate in SMTP TLS connection dave b (Mar 16)
- Re: Mutt: failure to check server certificate in SMTP TLS connection Joachim Schipper (Mar 08)