Stuck on AuthenticateAsServer method in mitm https proxy

Question

I'm trying to write a simple https mitm proxy, and the problem arises when I handle the request:

public async Task Run(NetworkStream client, NetworkStream host) {
        try {
            //getting the cert
            var certificate = new X509Certificate(@"[PATH_TO_CERT]", "[PASSWORD]");
            //creating client's Ssl Stream
            var clientStream = new SslStream(client, false);
            //there the program freezes
            clientStream.AuthenticateAsServer(certificate, false, SslProtocols.Default, false);

            //creating server's Ssl Stream
            var serverSslStream = new SslStream(host, false, SslValidationCallback, null);
            serverSslStream.AuthenticateAsClient("[HOSTNAME]");

            //...

        } catch (Exception ex) {
            Console.WriteLine(ex.Message);
            throw;
        }

    }

After the request from client is sent, the program freezes at this line

clientStream.AuthenticateAsServer(certificate, false, SslProtocols.Default, false);

and it doesn't throw any exceptions. At first I thought that the problem is in the client's stream, so I tried to pass it's TcpClient as a method parameter, but nothing changed.

My self-signed certificate and .pfx file has been created like that:

makecert -n CN=*.[HOSTNAME].com -ic MyCA.cer -iv MyCA.pvk -a sha1 -sky exchange -pe -sr currentuser -ss my SslServer.cer 
makecert.exe -pe -n "CN=*.[HOSTNAME].com" -a sha1 -sky exchange -eku 1.3.6.1.5.5.7.3.1 -ic CA.cer -iv CA.pvk -sp "Microsoft RSA SChannel Cryptographic Provider" -sy 12 -sv server.pvk server.cer

pvk2pfx -pvk MyCA.pvk -pi [PASSWORD] -spc MyCA.cer -pfx MyPFX.pfx -f

So I thought the problem is in this line

var certificate = new X509Certificate(@"[path to the cert]", "[password]");

I replaced the cer path to the pfx path and I even downloaded the original crt file new X509Certificate(@"[path to the original cert]");, but none of this worked.

I don't know where the problem is, I tried different clients, the result is the same.

My Visual Studio version is 15.7.27703.2018 and .Net is 4.7.1.

Any tips, suggestions or links that could help me?

It sounds like there may be no data coming in on the client stream. Perhaps just for testing, try reading a byte from the NetworkStream just to see if anything is transferred. Another option might be to do a network capture to see what is being sent. Might also want to check your Timeout settings. TcpClient and NetworkStream default to having no timeout, which may be causing it to look like the application is frozen, while in reality it could be timing out from having no data available. — Wiz, Jun 19 '18 at 17:18

score 0 · Accepted Answer · answered Sep 02 '18 at 12:55

Turned out that i needed to use it with await.

The final code looks like this:

//getting the cert
var certificate = new X509Certificate2(@"[PATH_TO_CERT]", "[PASSWORD]");
//creating client's Ssl Stream
var clientStream = new SslStream(client, false);
await clientStream.AuthenticateAsServerAsync(certificate, false, SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12 | SslProtocols.Ssl3, false);

Stuck on AuthenticateAsServer method in mitm https proxy

1 Answers1