Check_MK Werk 6846: More secure password hashing

ID: 6846 Title: More secure password hashing Component: Multisite Level: 2 Class: Security fix Version: 1.6.0i1 Passwords of local users of the Check_MK GUI are now hashed using SHA256 (salted, 535000 rounds) to increase the security of the stored user logon passwords. All existing users will still be able to login using their already hashed passwords. Once a user changes his password or a new user is created, these will be hashed using the new algorithm. Why SHA256? Check_MK supports different authentication frontends for verifying the local credentials: a) basic authentication (done by apache) and b) the GUI form + cookie based authentication. The default is b). This option is toggled with the "omd config" option MULTISITE_COOKIE_AUTH. In case the basic authentication is chosen it is only possible to use hashing algorithms that are supported by apache which performs the authentication in this situation. For best compatibility in all mentioned situations we use the SHA256 scheme.