[krbdev.mit.edu #8160] git commit

[Greg Hudson via RT]

Prevent requires_preauth bypass [CVE-2015-2694]

In the OTP kdcpreauth module, don't set the TKT_FLG_PRE_AUTH bit until
the request is successfully verified.  In the PKINIT kdcpreauth
module, don't respond with code 0 on empty input or an unconfigured
realm.  Together these bugs could cause the KDC preauth framework to
erroneously treat a request as pre-authenticated.

CVE-2015-2694:

In MIT krb5 1.12 and later, when the KDC is configured with PKINIT
support, an unauthenticated remote attacker can bypass the
requires_preauth flag on a client principal and obtain a ciphertext
encrypted in the principal's long-term key.  This ciphertext could be
used to conduct an off-line dictionary attack against the user's
password.

    CVSSv2 Vector: AV:N/AC:M/Au:N/C:P/I:P/A:N/E:POC/RL:OF/RC:C

https://github.com/krb5/krb5/commit/e3b5a5e5267818c97750b266df50b6a3d4649604
Author: Greg Hudson <ghudson at mit.edu>
Commit: e3b5a5e5267818c97750b266df50b6a3d4649604
Branch: master
 src/plugins/preauth/otp/main.c          |   10 +++++++---
 src/plugins/preauth/pkinit/pkinit_srv.c |    4 ++--
 2 files changed, 9 insertions(+), 5 deletions(-)