Viewing HTTPS Handshakes in Fiddler

You can easily use Fiddler to evaluate what algorithms a client is using to connect to a HTTPS server in Fiddler. First, adjust Fiddler’s configuration using Tools > Fiddler Options to enable capture of CONNECT tunnels but disable decryption: Disabling decryption is necessary because Fiddler decrypts traffic using a HTTPS man-in-the-middle technique, which means thatContinue reading “Viewing HTTPS Handshakes in Fiddler”

Fiddler Certificate Generators

Fiddler and FiddlerCore offer three different choices for generating interception certificates: MakeCert CertEnroll Bouncy Castle If you’re so inclined, you can even write your own certificate generator (say, by wrapping OpenSSL) and expose it to Fiddler using the ICertificateProvider3 interface. On Windows, Fiddler includes the MakeCert and CertEnroll certificate generators by default; you can downloadContinue reading “Fiddler Certificate Generators”

HTTPS Only Works If You Use It

It should be obvious, but everyone seems to be making the same mistake. HTTPS only works if you use it. Everywhere. If you don’t use HTTPS everywhere, a bad guy can intercept an insecure request and prevent the user from reaching your secure site. HSTS is a good start to mitigating the threat of accidentallyContinue reading “HTTPS Only Works If You Use It”

Testing HTTPS In Native APPs

Over on Twitter, Paul asks how to verify that a native application is using TLS. For a PC, it’s pretty simple, just run Fiddler and watch the traffic. If you see any HTTP requests (other than those labeled “Tunnel to”, indicating a HTTP tunnel used for HTTPS traffic) from the Process of interest, that trafficContinue reading “Testing HTTPS In Native APPs”