Is Yahoo Outsourcing Click Fraud Detection?

[StupidScript]

In the past month, we have started seeing a third-party click fraud detection outfit's URL increasingly in our log files. In fact, over this past weekend it became our number 1 'organic' referrer with more than double our #2 referrer's entries.

Since we only use Google's and Yahoo's PPC programs, and since Google has been developing their own click fraud detection system ... is this some kind of proof that Yahoo has finally outsourced their anti-click fraud programming?

(If a moderator assents, I'll post the referrer.)

The really irritating part is that this third party strips all keyword tracking codes before they send the click over to our system, so we have no way of determining either from where the fraudulent click came or which term the fraud is being perpetrated upon. We can't use the referrer data at all in our own fraud detection program as a result. All that remains when they are done is the root domain.