Please , could we learn some more about this attack ? Without being too much technical : Who made it ? , What means ? What for ?
just ask google and ther is a ton of info http://lmgtfy.com/?q=avast+forum+hack

https://blog.avast.com/2014/05/26/avast-forum-offline-due-to-attack/

How can I get informations on such a viral artillery ?
if you know the virus name you can search for info here https://www.securelist.com/en/ http://www.microsoft.com/security/portal/mmpc/default.aspx