It should be possible to obtain the set of property values shown on any of the Configuration > Servers and Sites > <server-id> > <tab> pages by sending a GET request to:
(where <server-id> is the deployment URL of OpenAM e.g. http://openam.example.com:18080/openam and <tab> can be any of the following: general, security, cts, advanced, session, uma, sdk, directoryconfiguration).
Unfortunately, attempts to do so fail as the URL encoded server ID (e.g. http%3A%2F%2Fopenam.example.com%3A18080%2Fopenam) seems to get stuck in CREST and results in a 400 Bad Request response.