I got an answer from one of the ad company : it's
not a local problem. It's companies that take buy 
a normal campagn and start sneaking-in such 
softwares during the weekend when advertising 
companies are closed and won't notice it.
It already happened sometime ago and that campagn 
was already canceled. Last weekend, it hapened 
again with many advertising companies, not just 
the one we use.

Cheers,
Yann Stettler