##Discourse Security Guide The following guide covers security regarding your Discourse installation ###Password Storage Discourse uses the PBKDF2 algorithm to encrypt salted passwords. This algorithm is blessed by NIST. There is an in-depth discussion about its merits in http://security.stackexchange.com/questions/4781/do-any-security-experts-recommend-bcrypt-for-password-storage. **options you can customise in your production.rb file** pbkdf2_algorithm: the hashing algorithm used (default "sha256") pbkdf2_iterations: the number of iterations to run (default is: 64000) ### XSS The main vector for XSS attacks is via the "composer", as we allow users to generate rather rich markdown we need to protect against poison markdown. For the composer there are 2 main scenarios we protect against: 1. Markdown preview invokes an XSS. This is severe cause an admin may edit a user's post and a malicious user may then run JavaScript in the context of an admin. 2. Markdown displayed on the page invokes an XSS. To protect against client side "preview" XSS, Discourse uses Google Caja https://code.google.com/p/google-caja/ in the preview window. On the server side we run a whitelist based sanitizer, implemented using the Sanitize gem https://github.com/rgrove/sanitize see: https://github.com/discourse/discourse/blob/master/lib/pretty_text.rb In addition, titles and all other places where non-admins can enter code is protected either using the Handlebars library or standard Rails XSS protection. ### CSRF CSRF allows malicious sites to perform HTTP requests pretending to be an end-user (without their knowledge) more at: http://en.wikipedia.org/wiki/Cross-site_request_forgery Discourse extends the built-in Rails CSRF protection in a couple of ways: 1. By default any non GET requests ALWAYS require a valid CSRF token. If a CSRF token is missing Discourse will raise an exception. 2. API calls using the secret API bypass CSRF checks 3. Certain pages are "cachable", we do not render the CSRF token (`