"The only way to clean up a network is to take it down from the internet and examine each computer, the way the Belgian foreign ministry has done.

There must be entire agencies in NATO countries that need the same procedure. All it takes is for one ignorant bureaucrat to click on an enticing link in an e-mail or plug in an unverified thumb drive, and the entire computer network becomes a giant hydrant blowing information to some server in Moscow, or wherever Snake's control center is.

It now transpires that Snake has been slithering silently around networks in the US and its NATO allies and former Soviet states for almost a decade, stealing data, getting ever more complex and modular and remaining almost invisible."

http://www.bloombergview.com/articles/2014-05-16/russian-cybersnake-may-be-putin-s-secret-weapon