You can purchase warranties from Subaru for the car depending on how many miles are on it.

And the factory standard warranty transfers to whoever as long as it's within the miles and term.

 

you can also buy a warrenty from a third party. i do not however have any additional information on it other than the fact that it can be done

 

The vehicle should still have factory warranty on it. What year is it, and how many miles does it have? The best extended warranty for a Subaru is Subaru's own Subaru Added Security. You can enquire about it at your local dealer or directly from SOA at 800-SUBARU-3.

 

I Would Be Careful Of What You Buy, I Have Seen Friends Buy 18,000 Dollar Pieces Of Junk, Dony By Somebody Elses Race Car Or Experiment. It Can Be Very Costly.

 

Dealers usually auction cars that they are unable to sell on their lots for some reason. If an 02-03 WRX is being auctioned there is probably something wrong with it.
At 50K the factory 3/36 warranty is long gone, there is still some time remaining on the 5/60 powertrain warranty but if the car has been modified and/or abused it may no longer apply.
It's probably too late to purchase an extended warranty as these usually must be bought while the car is still within the initial factory warranty period.
You are better off avoiding the auctions and looking for a privately owned one-owner car with few or no mods and good maintenance records. There are plenty of them around but it may take some time to find the right one.