问题
When using User-agent flow with OAuth2 for mobile platform, there is no way for Authorization server to authenticate the client_id of the application.
So, anyone can impersonate my app by copying the client_id (and so get all access tokens on my behalf), and this is applicable to Facebook, Foursquare,...
This is not managed by OAuth2 ? Or I missed something ?
For Web applications (Web server flow), access token is stored on the server side, and the client is authenticated using secret key.
回答1:
There's no good answer. Native app callbacks typically happen via custom registered URI schemes (e.g.: callback redirection URI is something like: myapp://oauth?code=xyz123). Unfortunately, any app can claim ownership of a given protocol scheme and receive the callback.
This problem is very synonymous with trying to lock down any protocol with "trusted clients". Think of the IM networks battle to lock out 3rd party clients (in early 2000's). Eventually they gave up - since whatever client & protocol endpoints are deployed could be reverse engineered by 3rd party developers.
Note: There is also some active discussion on this topic on the OAuth WG mailing list: http://www.ietf.org/mail-archive/web/oauth/current/msg08177.html
回答2:
Normally client_id is associated with site's URL - OAuth responses/redirects will be sent only to the registrated Url. So attacker will not be able to receive results of the request on own site (unless somehow your and attacker pages are on the same domain).
来源：https://stackoverflow.com/questions/8730590/oauth2-security-considerations-for-client-id