Junior Member Chatavi
This is strange because, according to the Symantic web site, Norton knows about Alcra B & F and, if your AV has the latest updates, should be able to take care of these worms.
Alcra B definition
http://www.symantec.com/security_res...062711-2417-99
Alcra F definition
http://www.symantec.com/security_res...021712-3034-99
I know this post does not directly answer your question but it should go someway to understanding what went wrong.
UK Bob