Oracle: DBA_PROXIES

select
   prx.proxy,                        -- Name of the proxy user
   prx.client,                       -- Name of the client user who the proxy user can act as
   prx.authentication,               -- Is proxy required to supply client's authorization credentials (YES, NO)
   prx.authorization_constraint,
   prx.role,
   prx.proxy_authority
from
   dba_proxies prx
where
   proxy = 'RNY'
;