Recently, we have encountered a problem while installing one of our applications for a customer. During installation the application needs to perform some requests to our cloud service and we realised it could not establish HTTPS connection: the very TLS handshake failed. After researching a bit we found the server was a Windows Server 2008 which does not support TLS v1.2, which is the minimum required to connect to our servers. There are some workarounds (this one, for instance) but none of them worked. In addition, we cannot install any update to that windows due to customer policies.
While looking for a solution, using wireshark, we noticed that our program tried to connect using TLS v1.2 and failed, but Chrome browser was able to connect to the same cloud server using TLS v1.3, which is not even supported in Windows Server 2008. From that we deduced that Chrome is likely using its own TLS stack to establish the connection.
I am wondering that if Chrome is doing that, we should also be able to do the same. The application is developed in .Net Core and I have googled a lot looking for information on how to do this, and I've found lots of information on how to configure TLS certificates in .Net Core, but none on replacing the TLS stack with, say, OpenSSL or others. I do know this is possible in Java, so is it possible to replace the TLS stack in .Net core?
.NET Core itself doesn't let you plug in your own crypto stack.
You pointed to Bouncy Castle as an example of Java letting you use an alternate crypto stack; there's a port of Bouncy Castle to C#/.NET as well.
Their source code has a test case that demonstrates how to write a TLS client using Bouncy Castle:
https://github.com/bcgit/bc-csharp/blob/master/crypto/test/src/crypto/tls/test/TlsClientTest.cs
Related
Having trouble with chrome v 4x.xx and WebLogic not automatically handshaking via tls 1.0 minimum. While calling a RESTful service from JavaScript front end I keep getting net::ERR_SSL_FALLBACK_BEYOND_MINIMUM_VERSION since Google have dropped support for SSL V3.0. I have tried adding the flag forcing this to JAVA_OPTIONS and on another occasion to the starting arguments for WebLogic, despite knowing these only become suported in 10.3.6. Is there another way?
So it turns out WebLogic 10.3.2.0 has a bug in it. When the client makes contact with the server for the first time it tells the server which SSL/TLS certificate version it supports - UP TO. The latest Chrome I believe supports TLS v1.2, so this is the only information sent to WebLogic. WebLogic has problems recognising that 1.2 is greater than 1.0, (which is the highest version available on WebLogic 10.3.2.0 (AFAIK, it is on ours) and should therefore be trusted, so terminates the connection.
source - https://productforums.google.com/forum/#!topic/chrome/iwX2PbNGk8E
We have clients who can be using anything, WindowsXP,Vista,Linux....
Currently our systems support SSLV2 and SSLV3.But, we are planning to disable both SSLV2 and SSLV3 in windows server 2008R2 in favour of TLS 1.2.
Will it have any breaking changes with the end user?I'm worried that If I disable SSLV3 ( and SSLV2) , some of the clients who use windowsXP(for example) might not be able to access my web service.
PS: Tried to find a similar question in stackoverflow, didn't find any. So, posting this as a question. :)
This is one of the scenarios where you will NOT be able to support old clients using insecure protocols and expect to have decent security.
If you have not enabled TLS 1.2 yet, do so.
Some clients do not support TLS 1.2 (e.g., older Android versions). You may need to support TLS 1.0 and 1.1 in addition to 1.2. While not ideal, it is definitely better than supporting SSL 2.0 and 3.0.
Post an announcement indicating that your web service is being upgraded to meet minimum security requirements and set a date for retiring insecure protocols.
Optionally, check your server metrics to see what protocols/ ciphers are used. Since you haven't mentioned your web server, I'm assuming it is IIS, in which case this is not easy[1][2].
Retire SSL 2.0 and SSL 3.0. There will be a few clients who will not be able to connect. Plan to have an answer ready for them. If you have clients running XP and using IE6, they have bigger issues than not being able to access your web service.
While you are at it, run your TLS configuration through an online
scanner like SSL Labs to ensure you fix any other issues.
I have a .NET application that uses the Background Intelligent Transfer service to upload files from a client Windows 7 X64 machine to a Windows 2012 R2 server. The server is locked down for TLS 1.2 for compliance with PCI 3.1, i.e. protocols SSL 2.0/3.0, TLS 1.0/1.1 have been explicitly disabled in the reigstry using IISCrypto and TLS 1.2 enabled. The client has a trusted Root CA certificate for the server installed on it.
The application uses the IBackgroundCopyManager and IBackgroundCopyJob COM interfaces to create the job and add it to the queue. In the Bits-Client event log, I see the following warning after it has started the the transfer (note that addresses and filenames are for illustrative purposes only):
BITS stopped transferring the test.tmp transfer job that is associated with the https://server/folder/temp.tmp URL. The status code is 0x80072EFE
The error code translates to:
ERROR_WINHTTP_CONNECTION_ERROR
12030
The connection with the server has been reset or terminated, or an incompatible SSL protocol was encountered. For example, WinHTTP version 5.1 does not support SSL2 unless the client specifically enables it.
This makes sense, as I can see in Wireshark that the BITS request is only ever trying to use TLS 1.0 in the handshake protocol with the server and this has been disabled.
My question is therefore: is it possible to enable the use of TLS 1.2 by the Bits-Client and if so, how is it done?
The COM interface does not provide any methods to set the protocol used and I cannot see anything in the registry settings for the BITS service either. It is definitely not a certificate issue as the transfers work as soon as TLS 1.0 is enabled on the server.
BITS goes over WinHTTP and uses the default WINHTTP_OPTION_SECURE_PROTOCOLS. The problem is that your client is running Windows 7. From MSDN:
By default only SSL3 and TLS1 are enabled in Windows 7 and Windows 8. By default only SSL3, TLS1.0, TLS1.1, and TLS1.2 are enabled in Windows 8.1 and Windows 10
See this support article for instructions on how to enable TLS 1.1 and TLS 1.2 on Windows 7 machines: https://support.microsoft.com/en-us/help/3140245/update-to-enable-tls-1-1-and-tls-1-2-as-a-default-secure-protocols-in
I have a C++ application that has a SSL/TLS communication with its own server and i don't have any access to that server. I'm trying to find out what is it sending from my PC to the server.
I tried burp and fiddler as man-in-middle but it didn't work. The application does not support Proxy so i tried routing the traffic using proxifier to burp and fiddler but it didn't work.
So I came up with these articles https://isc.sans.edu/forums/diary/Psst+Your+Browser+Knows+All+Your+Secrets+/16415 and http://ask.wireshark.org/questions/4229/follow-ssl-stream-using-master-key-and-session-id
I just need to know , How I can find Master-key and Session-ID to decrypt SSL/TLS trafic.
It depends on the TLS cipher suite being used. If the ciphersuite uses forward secrecy (DHE) you cannot decrypt the stream. If it uses RSA encryption then you need at least the private key of the server. If it also uses client authentication then you would also need the private key of the client. if it uses symmetric encryption you need the symmetric (master) key from either one of them.
But if you do have a C++ application, I would simply add logging to that application (at the lowest level).
You can use following alrternates on a x86 windows
STRACE - http://blogs.msdn.com/b/emmanubo/archive/2007/06/04/introduction-to-strace-httpreplay-support-tools.aspx
SOCKTRC if this app is on windows checkout
http://blogs.msdn.com/b/emmanubo/archive/2007/08/03/socktrc-tool.aspx
HTTPREPLAY -
generally used for browsers but here can be used to view the responses in the UI
I would like to display a message to customers who's browser's highest level of encryption is SSLv3. Is it possible for me to target browser settings of SSLv3 and lower? Client or Server code? We will be allowing lower versions of SSL to use our site during a certain grace period. During this grace period, we would like to display a message only to those users that have browser settings of SSL3 or lower.
Not easily. The browser's supported SSL versions are not detectable until the SSL handshake is in progress, and even then only if the browser uses an SSLv2 handshake to allow dynamic version negotiation. If an unsupported version were detected, you would not be able to send a message back since the handshake failed and the connection would be closed before you could send any message. However, SSL itself has an error packet that gets sent during handshaking, and it can specify a version mismatch error.
The best you can do in your own code is support all SSL versions on the server side, let the client complete a handshake normally, and then detect which version was actually used and send back a message if the SSL version is too low.
Or, you could simply enable TLSv1 or higher only, and simply refuse to let older clients connect at all. They just would not get a nice error message unless the browser decided to detect the SSL version mismatch error and display its own pretty message about it.
Firstly, nowadays, you can generally forget about clients that don't support at least SSLv3. SSLv3 has been widely available for many years.
The TLS Client Hello message, sent when the connection is initiated by the browser, should contain the highest TLS version it supports:
client_version
The version of the TLS protocol by which the client wishes to
communicate during this session. This SHOULD be the latest
(highest valued) version supported by the client. For this
version of the specification, the version will be 3.3 (see
Appendix E for details about backward compatibility).
Appendix E is of course worth looking at.
(The Client Hello message will also contain the list of cipher suites the client supports, which is possibly relevant for the general idea of your question.)
Of course, this specification is just a "SHOULD", so a client supporting TLS 1.2 could still send a Client Hello for TLS 1.1, but what would be the point? By doing so it would have no chance ever to use TLS 1.2 anyway. It could be a preference box that is turned off, but that would effectively make it a client that doesn't support the highest version anyway. (If you want anything more subtle, you'd need to build a database of known user agents, which will be partly unreliable, and for which you'd need to analyse the full user agent string to know everything possible about the platform.)
Now, how to convey the content of the Client Hello message to your application is another matter, and depends very much on which SSL/TLS stack you use. It might not even be directly possible without modifying that SSL/TLS library or the server you're using.
This being said, you can generally get the negotiated TLS version during the current session quite easily. Since that version is the "lower of that suggested by the client in the client hello and the highest supported by the server" (i.e. "min(max(client), max(server))"). If your server supports SSLv3, TLS 1.0, TLS 1.1 and TLS 1.2, and since the latest version is TLS 1.2 anyway, what you'll get during your current connection will also be the max currently supported by the client. As long as your server supports the latest version, you should be able to know what the client supports at best from any live connection.
If you're behind Apache HTTP server's mod_ssl, you should be able to get that from the SSL_PROTOCOL environment variable. You should also be able to get the protocol from the SSLSession in Java.
(If you are willing to write a more bespoke service, you could pass further details like the cipher suites more directly to your application, like this service from Qualys SSL Labs does, although I'm not sure if it's meant to be widely available or just a test service.)
I'd have to agree with Remy about it being a bit challenging.
However, a good starting point may be to retrieve some SSL (certificate) information.
Something similar to this:
X509Certificate certChain[] =
(X509Certificate[]) req.getAttribute("javax.net.ssl.peer_certificates");
Another way of getting more information is to retrieve the cipher_suite attribute (similar to the code snippet above).
javax.net.ssl.cipher_suite
I hope this (at least) gets you closer.
Good luck.