[openssl-dev] [openssl.org #4511] s_server does not send Alert messages upon receiving malformed Client Key Exchange messages in DHE key exchange

[Hubert Kario via RT]

On Friday, 15 April 2016 13:22:52 CEST Hubert Kario via RT wrote:
> Using either current 1.0.1 or 1.0.2 branch (7a433893a and 9676402c3a
> respectively) openssl s_server command does not send Alert message upon
> receiving a malformed or invalid Client Key Exchange message in DHE key
> exchange.
> 
> That applies to messages that are longer and shorter than needed as well
> as messages that include client key shares bigger than the prime selected
> by server.

the issue is still present in master 0ed26acce328ec16a3aa
 
Reproducer:
===========
(requires Python 2.6, 3.2 or later)
git clone https://github.com/tomato42/tlsfuzzer.git
pushd tlsfuzzer
git clone https://github.com/warner/python-ecdsa .python-ecdsa
ln -s .python-ecdsa/ecdsa ecdsa
git clone https://github.com/tomato42/tlslite-ng.git .tlslite-ng
pushd .tlslite-ng
popd
ln -s .tlslite-ng/tlslite tlslite
popd
openssl req -x509 -newkey rsa -keyout localhost.key -out localhost.crt \
-nodes -batch -subj /CN=localhost openssl s_server -www -key localhost.key \
-cert localhost.crt
# in another terminal, same directory
PYTHONPATH=tlsfuzzer python
tlsfuzzer/scripts/test-dhe-rsa-key-exchange-with-bad-messages.py


-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic
-- 
Ticket here: http://rt.openssl.org/Ticket/Display.html?id=4511
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