Microsoft, Google, Cisco, VMware join legal battle against hacking company NSO

Tech giants Microsoft, Alphabet , Cisco, and VMware on Monday joined Facebook's legal battle against hacking company NSO, filing an amicus brief in federal court that warned that the Israeli firm's tools were "powerful, and dangerous."

The brief warns that the growth of "a robust, unchecked, commercial market for cyber-surveillance tools would dramatically increase the number of governments and private companies with access to them." Facebook took the unusual step of suing NSO last year after it was revealed that the cyber surveillance firm - whose programs take advantages of software weaknesses to hijack targets' devices - had exploited a loophole in the code of Facebook-owned chat application WhatsApp to help surveil more than 1,400 people worldwide.

NSO - which did not immediately return a message seeking comment - has argued that it can claim immunity from the lawsuit by virtue of the work that it does for foreign governments. The case is being closely watched by human rights defenders and technologists, many of whom have long warned that NSO's services were being used to harm innocents and stifle political dissidents.