Thomas Henlich wrote:
Sequence of attack
- S sends EHLO response with STARTTLS advertisement.
- A4 discards S's STARTTLS advertisement.
- PLAIN authentication takes place.
- A4 can read cleartext password.
RESOLUTION
For A1-A3 no resolution is known. For A4, set user preference to
enforce TLS.
Comment about A4.
Thunderbird explicitly allows you "TLS, if available" - which appears to
be what you refer to. However, there is a "TLS" - which means only do
TLS - and alert if the TLS certificate presented doesn't match a known
one (which would happen in a MITM).
Are you referring to a bug in their "TLS" mode - or implying that "TLS,
if available" is somehow not... what it says it is...???
Doesn't sound like a hole to me.
--
Cheers
Jason Haar
Information Security Manager, Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417
PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1
