When Shane Macaulay tried to sell the Fujitsu U810 laptop he won in a hacking contest last week, it seemed almost like an April Fool's joke.

He said that a top-quality hacker could probably examine the machine's hard drive and dig up the unpatched zero-day exploit code he had used to compromise the computer in the PWN 2 OWN contest that he'd just won. "This laptop is a good case study for any forensics group/company/individual that wants to prove how cool they are, and a live example, not canned of what a typical incident responce sitchiation [sic] would look like," he wrote in his listing.

At first blush, this seemed like a clear violation of both the rules of the contest's sponsor, TippingPoint, and of eBay's terms of service, and his listing was pulled within hours by eBay staff. The company said it had to go because it could have harmed users.

But Macaulay says that was never his intent. In a Tuesday interview with IDG News, he explained that Adobe Systems plans to patch his Flash bug on April 8, the day his auction was set to end, so he would have been practicing responsible disclosure, releasing details of a flaw that had already been patched. The following is an edited version of this interview.

IDG News Service: Why did you try to sell this laptop on eBay?
Shane Macaulay: I wanted to get a sense for what a market price would be for a zero-day exploit. It's really hard to get that. To get a true price on it violates the policy of eBay, so I had to make limited disclosures to them and then limited disclosures to the vendors and other groups to allow that to happen.

IDGNS: Why were you wondering about that?
Macaulay: I've been involved in several attempts to make a sale of these sorts of items to groups that have presented themselves to me as being legitimate users of these things. You give them the exploit or the zero-day code, and they want to evaluate it themselves before they pay you. So you can imagine how that goes. You have no leverage in your sale and they change their price... and the person who spent all this time and investment personally into this item loses the ability to make any money.

IDGNS: Were you surprised that eBay took your auction down?
Macaulay: No, because I was a little rushed in my posting. I've got an e-mail group list [at eBay] that I was going to apply to earlier in the process and at least apprise them of the background story, and say, "Hey this is going to be in line with the disclosure process of this vendor and [contest sponsor TippingPoint's] Zero Day Initiative. So by the time this closes, it's going to be non-zero-day."

It was going to afford me the chance to get at least a bidding process where the bidders were bidding while it was zero day.