Cybercriminals used existing malware called “DarkSeoul,” changed its signature to evade firewalls and antivirus software. The malware was capable of infecting Windows, Unix and Linux servers, as well as PCs. The origin of the South Korea attacks is not known. Companies need to think about security as not just stopping an attack from the outside, but uncovering malware once it gets in, experts say. In the U.S. bank attacks, the motivation appears to be harassment and constant probing for weaknesses, one expert says.”]