551175 - "connection was interrupted" on unsupported SSL cypher

Status: RESOLVED INVALID

(Firefox :: General, defect)

Description

[denyipanyany]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)

If I set Firefox to only allow certain SSL cyphers (such as only allowing AES 128 or 256) and then try to view a HTTPS site that only supports RC4, I get a 'The connection to que.campuscu.com was interrupted while the page was loading.' There is no indication that my SSL cypher limits are causing the issue.

Reproducible: Always

Steps to Reproduce:
1. Only allow AES128/256 encryption
2. Visit a site that has (max) RC4128
3. Witness vague error message
Actual Results:  
Firefox gives a 'The connection was interrupted' page

Expected Results:  
A error page that explains the SSL cypher isn't compatible, and maybe an easy way to turn on the strongest-supported cypher that the site supports.

I disabled all non-AES SSL cyphers in order to test this behavior.

Comment 1

[denyipanyany]

Please note; With only AES SSL enabled, I see the same (bad) behavior at "https://ppc.floridatelco.org". However Firefox behaves as expected when trying to "view https://www.bankofamerica.com/index.jsp" by giving back a "Secure Connection Failed    Error code: ssl_error_no_cypher_overlap", which should be the behavior when viewing either "bad" example site.

Comment 2

[Jo Hermans]

It's possible that it was the remote site closed the connection to the browser when it detected that there was no overlap between the cyphers, instead of returning a proper error code.

(just guessing)

Comment 3

[denyipanyany]

Upon inspection with Wireshark, it does seem that the 'bad' server returns a FIN upon receiving a non-supported Encryption, as opposed to a 'Handshake Failure' like a 'good' server does. It appears its a server-side problem, and Firefox does behave as expected when the server behaves well. Feel free to close as invalid.

Comment 4

[Jo Hermans]

ok. It's not the first time that issues like this show up - if there's no specific error-message from the server, all the browser can do is to tell the user that the connection was unexpectedly closed.