Shill bidding is the act of using bids in an online auction to drive up the fil price for the seller, thereby defrauding legitimate bidders. While 'shilling' is recognized as a problem and shill bidding is strictly forbidden in online auctions, presently there is little to no established means of defense against shills. This paper presents a software bidding agent that follows a shill bidding strategy. The agent incrementally increases an auction's price, forcing legitimate bidders to submit higher bids in order to win the item. The agent ceases bidding when the desired profit from shilling has been attained, or in the case that it is too risky to continue bidding without winning the auction. Its ability to inflate the price has been tested in a simulated marketplace and experimental results are presented. Furthermore, the agent is used to assist in developing algorithms to detect the presence of shill bidding in online auctions.