I did understand the discussion. I was just making the point that when
one does cram-md5 as opposed to plain or login that the password travels
across an encrypted tunnel in all instances; however, the difference
between 587 and 465 is that 587 does not start as an encrypted session,
465 does.
On 1/27/2019 8:35 PM, Andrew Swartz wrote:
Eric,
I use port 465/TLS for submission, so I agree completely with you.
But I think the discussion was regarding using port 587/STARTTLS. In
that setting, STARTTLS is vulnerable to a downgrade attack which
tricks the conversation to authenticating without the STARTTLS
encryption. So if one uses STARTTLS, one must rely on the SMTPAUTH
encryption (cram-md5). However, that too is vulnerable (dictionary
attack, I believe). This is the reason the RFC now recommends port
465/TLS.
At least, that's my understanding.
-Andy
On 1/27/2019 6:19 PM, Eric Broch wrote:
The password encryption is inside an encrypted tunnel. IMHO opinion
it's really quite useless.
On 1/27/2019 8:16 PM, Andrew Swartz wrote:
Ahhh... that's right.
But then the next question is should one use cram-md5? I believe it
is currently considered insecure.
I just found this link which explains the qmail SMTPAUTH options:
https://www.fehcom.de/qmail/smtpauth.html##SETUP
Unless there is a newer patch, it looks like cram-md5 is the only
password encryption option.
-Andy
On 1/27/2019 11:20 AM, Philip Nix Guru wrote:
Hello Andy
it is indeed a parameter you set in the env variable in the run
file (in my case I set it up in the submission run file)
cat /var/qmail/supervise/submission/run
#!/bin/sh
QMAILDUID=`id -u vpopmail`
NOFILESGID=`id -g vpopmail`
MAXSMTPD=`cat /var/qmail/control/concurrencyincoming`
SMTPD="/var/qmail/bin/qmail-smtpd"
TCP_CDB="/etc/tcprules.d/tcp.smtp.cdb"
HOSTNAME=`hostname`
VCHKPW="/home/vpopmail/bin/vchkpw"
export SMTPAUTH="!+cram" <<<<<<<<<------------------
exec /usr/bin/softlimit -m 128000000 \
/usr/bin/tcpserver -v -R -H -l $HOSTNAME -x $TCP_CDB -c
"$MAXSMTPD" \
-u "$QMAILDUID" -g "$NOFILESGID" 0 587 \
$SMTPD $VCHKPW /bin/true 2>&1
The current _qmail-authentication_ patch allows you to use the
environment variable SMTPAUTH for *qmail-smtpd* in the following way:
SMTPAUTH settings for *qmail-smtpd
* *SMTPAUTH* *Meaning*
"" Left blank to allow Authentication types "PLAIN" and "LOGIN"
"+cram" Add "CRAM-MD5" support
"cram" Just (secure) "CRAM-MD5" support, no other types offered
"!" Enforcing SMTP Auth (of type "LOGIN" or "PLAIN")
"!cram" Enforcing SMTP Auth of type "CRAM-MD5"
"!+cram" Enforcing SMTP Auth of type "LOGIN", "PLAIN", or
"CRAM-MD5"
"-" Disabling SMTP Auth (for a particular connection)
The complete patch info is listed here :
https://www.fehcom.de/qmail/smtpauth.html
Regards
-P
On 1/26/19 8:06 PM, Andrew Swartz wrote:
My guess is that there must be a difference in the patches applied
to qmail-smtpd or a different compile time option. I don't think
this is a simple setting (like in qmail/control).
When the connection comes in, tcpserver forwards it to
qmail-smtpd. If STARTTLS is invoked, qmail-smtpd hands that task
off to openssl, which then returns the decrypted plaintext. But
the password processing, whether plain, login, or encrypted, is
likely handled directly by qmail-smtpd.
Is anyone out there familiar enough with the source code to
confirm or refute this?
If it is a compile option, it should be fixable with mild to
moderate effort. If it is a patch change, that seems more
difficult (at least with my skill level).
If you figure this out, please let us know, as others will likely
be making the migration in the future.
-Andy
On 1/25/2019 1:21 AM, Philip Nix Guru wrote:
I tested with Thunderbird (where the account was working fine
with stable version and encrypted password on starttls)
and the message came up after the upgrade to change to normal
password.
When lamba users will get that message they ll just panic and
wont know what to do.
I still need to check how outlook will react ...
On 1/25/19 10:52 AM, Tommi Järvilehto wrote:
Was there a problem with Outlook and encrypted passwords? Or the
password cache?
On 25.1.2019 11:43, Philip Nix Guru wrote:
Hello
Yes that's one of the reason I was wondering why encrypted
password was no longer supported for STARTTLS in the lastest
dev version
Regards
-P
On 1/25/19 8:56 AM, Andrew Swartz wrote:
I would add the caveat that STARTTLS is only "probably safe".
Unfortunately, it suffers from a critical error in the very
concept of going from an plaintext session to a TLS session,
resulting in an unfixable (as far as I know) vulnerability. A
man-in-the-middle can inject text into the server response to
tell the client that STARTTLS is not available and that the
conversation should therefore continue in plaintext. I've
read that several ISP's have been caught using this
vulnerability to scan people's outgoing email. That means
PLAIN or LOGIN type submission passwords can be seen.
This is why the 2018 RFC (https://tools.ietf.org/html/rfc8314)
has strongly recommended abandoning STARTTLS on port 587 and
using dedicated TLS on port 465 for mail submission.
-Andy
On 1/24/2019 9:30 PM, Eric Broch wrote:
The password is not encrypted (Normal) but is sent over an
encrypted connection, it's safe.
On 1/24/2019 5:39 PM, Philip Nix Guru wrote:
Hello
I was testing the dev version (an upgrade over the stable
version) and came through that annoying problem
if I have to advise all users to change their config :
Sending of the message failed.
The Outgoing server (SMTP) xxxxxx does not seem to support
encrypted passwords. If you just set up the account, try
changing the 'Authentication method' in 'Account settings |
Outgoing server (SMTP)' to 'Normal password'.
All the users having a starttls config in their mail client
had to change from encrypted to normal
which of course brought the question "oh it is not safe
anymore ..."
Regards
-Philip
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