Re: Bug in SSLv3 protocol using SSLv23 method?

[Richard Levitte - VMS Whacker]

From: Claus Assmann <[EMAIL PROTECTED]>

ca+ssl> Me again... sorry to bother you.  I still have a problem with the
ca+ssl> MTA at mail.stalker.com. The developer from Stalker was very helpful
ca+ssl> and he concluded there is a bug in OpenSSL.
ca+ssl> 
ca+ssl> Here is his e-mail:
ca+ssl> 
ca+ssl> ! We have added the check for the "premaster secret" verification.
ca+ssl> ! According to the SSL/TLS standard, the first 2 bytes of that secret
ca+ssl> ! should be the protocol version. Since CgatePro insists on TLSv0 (aka
ca+ssl> ! SSL 3.0), the OpenSSL correctly switches to that protocol. But - forgets
ca+ssl> ! about it in the premaster secret: the first 2 bytes there show "3" "1",
ca+ssl> ! instead of "3" "0".
ca+ssl> 
ca+ssl> I have to admit I couldn't find this from a brief look. If you need
ca+ssl> the logfile, I can send it to you, but it is easy to reproduce using
ca+ssl> the starttls application
ca+ssl> 
ca+ssl> openssl starttls -connect mail.stalker.com:25 -debug

To begin with, whic OpenSSL versoin was used?  You may have written
that before, but I can't find that info.

Anyway, I'm a bit surprised you get that result, because looking at
lines 567 and 568 in s3_pkt.c (in the current development snapshot),
but the major and minor version number are copied from the SSL
structure given to do_ssl3_write().  So basically, it would mean that
if the version number was correct before the key exchange, it was
somehow changed to 0x0300 sometime before that.

What you can do, if you'd like, is to debug the program and look at
the SSL structure that is passed to do_ssl3_write(), or trace all
changes to the version field in the SSL structure you use, and see if
you catch it.

BTW, the starttls command is unknown to me, but then again, I may have
missed something...

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