SSH/HTTP(S) multiplexing with sshttp

Sebastian Krahmer (@steaIth, c-skills) made and released a nice SSH/HTTP(S) multiplexer: sshttp. Such a program is needed when you want to share your HTTP (or HTTPS) port with SSH to be able to use SSH when behind a network that only allows outbound connections to HTTP (or HTTPS) and does not bother to do protocol inspection. Learn more by reading the readme.

I was previously using sslh but sshttp has a killer feature: it uses Linux IP_TRANSPARENT feature with netfilter trickery (marking + specific routing table) to pass the original IP to destination (sshd or httpd) which means your logs still show original IP (and not 127.0.0.1). Since it's a great program, not necessarily easy to set up (not yet? packaged), in this post I'm sharing my setup.

HSTS preloading, public key pinning and Chrome

I recently discovered Chrome's net-internals. Among other interesting things, there is a tab about HTTP Strict Transport Security (HSTS). Also, introduced with version 12/13, Chrome now has HSTS preloading and public key pinning. These two features helps improve online security:

• HSTS preloading: browser already knows if a site has to be contacted via HTTPS only. For instance, it ensures users go to https://site even if they type http://site. This protects against MITM attacks when reaching http://site for the first time (see how sslstrip strips the "s" of https).
• public key pinning: certificate chain must include a whitelisted public key. For instance, it ensures only whitelisted Certificate Authorities (CA) can sign certificates for *.example.com, and not any CA in your browser store.

Write-up Codegate 2010 #7 - Decrypting HTTPS SSL/TLSv1 using RSA 768bits with Wireshark

Last week-end, I was a challenger at Codegate 2010 Capture the Flag with team Nibbles. Well organized by Koreans guys (who didn't sleep a lot either ;), the CTF proposed quality challenges and I thought it would be a great subject for a few posts.

Challenge #7 was a network capture file (ssl.pcap) containing an encrypted https session. The hint was: does the modulus look familiar?. The goal is obviously to decrypt the https to find the flag. Let's see how we can do that!

Steps:

1. Extract public certificate
2. Identify encryption
3. Create private certificate
4. Decrypt https