Pharma attack in italian-latin

Hi everybody

I think i’ve discover a new attack… I search some similar cases but i’ve found nothing…

This time the hackers modify only the description of some of your best SERPs.
They add a italian-latin language mixed with pharma words. You can see an example of hacked sites searching:

1) https://www.google.es/search?q=%22Caratteristiche+il+verr%C3%A0+grande+oltre+pensano+l%27+vasai%22&ie=utf-8&oe=utf-8&gws_rd=cr&ei=5nQGVtDEM8K7ad7sraAO
2) https://www.google.es/search?q=%22San+italiana+crisi+sottoposta+come+un+sisto+particolare%22&ie=utf-8&oe=utf-8&gws_rd=cr&ei=dHYGVrnRKIGaae2gi6AO
As you can see there are pharma words inside the description.
Only Google Bot can see this phrases and link, a normal user see a normal page (look the cache result if you want to look how google bot see the hacked page).
They simply change your title description.

Now… my site is hacked in this way and i spend so much hours to understand how they do it, but i’ve not found solutions. Anybodoy has a similar case? Any idea?

Best regards to all