The FBI has used a court order to cut off hackers' access to a network of US computers used to infiltrate diplomatic and military agencies of 50 Nato countries and allies for over 20 years.
The FBI operation and US public advisories said it would now be “difficult or/and untenable” for Russia's domestic intelligence service (FSB) to effectively use it again.
The news is the latest on a series of actions taken by US authorities to crack down on foreign spying and criminal rings using custom-built FBI tools.
"We assess this as being their premier espionage tool," one of the US officials told journalists. He said Washington hoped the operation would "eradicate it from the virtual battlefield."
The malware, known as Snake, was said to have been designed by a notorious hacking group tracked by the private sector, named Turla. This is widely believed by experts to be one of the most elite cyber-espionage units in the Russian intelligence...