Indeed - Knox writes in her book about the harrowing experience of having the authorities photograph her genitals in detail, and her naked body in general, soon after she was taken into custody. If it's these photos that are the ones in issue (assuming for a moment, therefore, that Knox had not taken, or had taken, her own erotic photos of her own body some time previously, which were either sitting on her computer or that she'd sent to someone else), then clearly the primary source for the photos would have been the law enforcement authorities.
It's entirely possible that the photos were included in the evidence bundle that was passed to the defence lawyers, to which Knox's family would also have had access. But even if that were the case, the only way that the defence "side" could have been responsible for any possible leak and attempted sale would be if either a) Knox's lawyers or her family had tried to sell the photos (vanishingly unlikely of course), or if Knox's lawyers or her family had for some reason passed these photos onto a third party (a "blogger", perhaps) who in turn had tried to sell them. But then one would have to ask why Knox's lawyers or her family would have been passing such photos over to "bloggers" in the first place.
Or....... the photos were leaked from a porous and corrupt part of the Italian law enforcement community (for a good precedent, see also the sale of crime scene photos taken on a private camera by one of the investigating police officers.......) - either by a corrupt policeman or by someone within the prosecutor's office, neither of whom would owe any duty of allegiance or sympathy to Knox, and either of whom therefore would probably have few qualms about trying to make money out of selling nude photos of her (albeit harrowing, clinical photos with roughly zero erotic value).
Hmm. I wonder which of those alternatives makes more sense, when everything's analysed properly............?