Mutt: failure to check server certificate in SMTP TLS connection

2011.03.18
Credit: dave b
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-20


CVSS Base Score: 5.8/10
Impact Subscore: 4.9/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: None

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).

References:

http://seclists.org/fulldisclosure/2011/Mar/87
http://xforce.iss.net/xforce/xfdb/66015
http://www.securityfocus.com/bid/46803


Vote for this issue:
50%
50%


 

Thanks for you vote!


 

Thanks for you comment!
Your message is in quarantine 48 hours.

Comment it here.


(*) - required fields.  
{{ x.nick }} | Date: {{ x.ux * 1000 | date:'yyyy-MM-dd' }} {{ x.ux * 1000 | date:'HH:mm' }} CET+1
{{ x.comment }}

Copyright 2018, cxsecurity.com

 

Back to Top