Have a question regarding weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message.

Hopefully this is an easy fix as I don't truly understand ciphers etc...

We have a spam filter (Websense).  Our users get emailed a link daily allowing them to see what spam they have.  If they use Firefox they get an error message with the following:

An error occurred during a connection to c*****:8443. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. (Error code: ssl_error_weak_server_ephemeral_dh_key)

    The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
    Please contact the website owners to inform them of this problem.


Is the issue on the server end or in Firefox?  I've installed IIS Crypto on the Server so I can see protocols, ciphers, cipher suites, Hashes Key Exchanges etc but am unsure on what to do.  I also have seen the work around where you can go into the config of Firefox and change some setting to false to bypass some of the security settings but this doesn't seem like a practical solution.


Ideas or help?


fwiw users with Chrome get a similar message but IE and Opera users can connect fine?


Thanks
BlueGooseAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Sean JacksonInformation Security AnalystCommented:
I'm not 100% sure, but make sure all the browsers are up dated to the current version, and make sure the server has these ciphers enabled:

TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA
0
footechCommented:
The cause is that you are using ciphers on the server side that the latest versions of Firefox and Chrome have deprecated.  So you can either change the setting on the Firefox side to allow the use of the cipher(s), or change the server side to not use those.

If I remember right, the settings for Firefox are
security.ssl3.dhe_rsa_aes_128_sha
security.ssl3.dhe_rsa_aes_256_sha

So if you disable those on the server side you should be good.  I think those would equate to
TLS_DHE_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_RSA_WITH_AES_256_CBC_SHA

If the server is accessible via the internet, I would advise checking it against https://www.ssllabs.com/ssltest/
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
BlueGooseAuthor Commented:
It ended up being an issue on the server side.  My vendor needed to load a new xml file that was compatible with the new security that Firefox has in it's latest update
0
BlueGooseAuthor Commented:
I've requested that this question be closed as follows:

Accepted answer: 0 points for BlueGoose's comment #a40997706

for the following reason:

Ended up being a server side issue and nothing to do with the browser
0
BlueGooseAuthor Commented:
Assigning points as you did mention in your answer that the issue may lie on the server side
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Microsoft IIS Web Server

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.