Naden, whose place in Penrith's game-day 17 was one of the storylines of grand final week, admitted using the recreational drug to club officials last month.
His positive A-sample for "metabolites of cocaine" was registered in a post-game test conducted by Sport Integrity Australia after the October 25 decider.
Cocaine is prohibited in-competition by both the World Anti-Doping Agency (WADA) and the NRL's Anti Doping Policy, with Naden now serving a provisional suspension as a result.
