1334836 - Thunderbird accept insecure TLS and email configuration without warn the user

Status: UNCONFIRMED

(Thunderbird :: Security, defect)

Description

[u534134]

Attachment: 1.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:51.0) Gecko/20100101 Firefox/51.0
Build ID: 20170125094131

Steps to reproduce:

I have Fastweb email configured on Thunderbird and PosteCert email.

Thunderbird never alerted me about security issue on this two email configuration provider, just today, when I try to configure this email address to K9mail app I discover that email account are not allowed to work on K9mail because is strongly insecure.

Please see here: https://github.com/k9mail/k-9/issues/2149#issuecomment-275876955


Actual results:

Thunderbird allow insecure email account without warn user about security risk


Expected results:

Thunderbird should block insecure email account or warn the user and let decide if use or not.

Comment 1

[u534134]

Attachment: 2.png

Fastweb insecure screen. No warn from Thunderbird

Comment 2

[Magnus Melin [:mkmelin] (away until Aug 10)]

I don't know where you say it does that. If I try to set up an [e-mail] address it gives no suggestions.

Comment 3

[Onno Ekker [:nONoNonO UTC+1]]

When using STARTTLS, you can configure Thunderbird to always use STARTTLS or to use STARTTLS if available. The latter silently uses an unencrypted connection when there's no TLS available, although I seem to remember that you get a warning when setting up the connection with that setting.
See also http://kb.mozillazine.org/Secure_connections_-_Thunderbird for more information.

Comment 4

[Magnus Melin [:mkmelin] (away until Aug 10)]

"STARTTLS, if available" is only available for very old accounts (pre 2008 or so). You can't set it for new ones.

Comment 5

[Daniel Veditz [:dveditz]]

A bunch of people might have those settings: do we need to warn them or migrate them? Add an insecure warning if starttls fails for those folks?

In other words is this bug "works as designed (for old accounts)" or "there's something we should do here" ?

Comment 6

[Magnus Melin [:mkmelin] (away until Aug 10)]

For reference, the "if available" option deprecation and hiding if you didn't have it set was done in bug 350314.

As I recall, at least at the time we didn't dare to upgrade to STARTTLS (only) since apparently some servers advertised support but didn't really work. 

For new accounts you are able to select unencrypted, but that comes with a big warning. I don't think there is anything to do here.

---

But, was this really what this bug was about? In the link there's the comment "Looks like the servers only support TLS ciphers we consider insecure. Tell your email providers they need to step up their security game if they want K-9 Mail users to be able to connect to their servers."

https://www.htbridge.com/ssl/?id=a05f5eb0769f1a6a3b59b9bfdcd6bfcab5a77defe5ef0265550f9776d58ef617
https://www.htbridge.com/ssl/?id=dc958dd0c69ef7e80e70fa0ccd6cf295d53b2ea0b585e990e90504582ad6128c

... and that seems to think the main error is "The server supports a client-initiated insecure renegotiation that is unsafe and may allow Man-In-The-Middle attacks."

So all in all I'm a bit confused to what the problem is supposed to be. That we support STARTTLS at all?

Comment 7

[Daniel Veditz [:dveditz]]

This is not a bug that needs to be hidden. It's a UX design decision about what to expose to users, but known-bad-crypto mail servers are already known and will be attacked regardless of the user's settings.

Comment 8

[u534134]

(In reply to Magnus Melin from comment #6)
> For reference, the "if available" option deprecation and hiding if you
> didn't have it set was done in bug 350314.
> 
> As I recall, at least at the time we didn't dare to upgrade to STARTTLS
> (only) since apparently some servers advertised support but didn't really
> work. 
> 
> For new accounts you are able to select unencrypted, but that comes with a
> big warning. I don't think there is anything to do here.
> 
> ---
> 
> But, was this really what this bug was about? In the link there's the
> comment "Looks like the servers only support TLS ciphers we consider
> insecure. Tell your email providers they need to step up their security game
> if they want K-9 Mail users to be able to connect to their servers."
> 
> https://www.htbridge.com/ssl/
> ?id=a05f5eb0769f1a6a3b59b9bfdcd6bfcab5a77defe5ef0265550f9776d58ef617
> https://www.htbridge.com/ssl/
> ?id=dc958dd0c69ef7e80e70fa0ccd6cf295d53b2ea0b585e990e90504582ad6128c
> 
> ... and that seems to think the main error is "The server supports a
> client-initiated insecure renegotiation that is unsafe and may allow
> Man-In-The-Middle attacks."
> 
> So all in all I'm a bit confused to what the problem is supposed to be. That
> we support STARTTLS at all?

Security issue is that Thunderbird works well also if the connection with a server is insecure because use old TLS or bad chippers suite.