The companies filed a voluntary memorandum in federal court warning that the Israeli company’s tools were strong and dangerous.
The memo, filed with the U.S. Court of Appeals for the Ninth Circuit, opens a new front in Facebook’s lawsuit against NSO.
Facebook filed the lawsuit last year after it was revealed that the electronic monitoring company had exploited an undeclared security flaw in Facebook’s WhatsApp program to penetrate the devices of more than 1,400 people around the world.
NSO explained that it sells digital hacking tools to police and spy agencies, and should benefit from sovereign immunity, a legal argument that generally protects foreign governments from lawsuits.
The NSO lost that argument in Northern California in July, and has since appealed to the U.S. Court of Appeals for the Ninth Circuit to overturn the ruling.
Microsoft, Google, Cisco, VMWare and the Washington-based Internet Society joined Facebook against the electronic monitoring company.
The companies said: Granting NSO sovereign immunity is leading to the spread of hacking technology and providing more foreign governments with powerful and dangerous electronic surveillance tools.
That, in turn, means dramatically more chances for those tools to fall into the wrong hands and be used outrageously.
The Israeli company says: Its products are used to fight crime, and that is why it must obtain legal immunities because it works on behalf of governments.
Human rights defenders and technologists in places like Amnesty International and Citizen Lab have documented cases in which NSO technology has been used to target reporters, lawyers, and even nutritionists pushing to tax soft drinks.
NSO sells governments access to Pegasus spyware, allowing nation-state clients to target and penetrate target devices.
Spyware, such as Pegasus, can track the victim’s location, read his messages, listen to his calls, steal his photos and files, and pull private information from his devices.
Microsoft Chief Customer Security and Trust Tom Burt said in a blog post, “NSO should be responsible for the tools it creates and the vulnerabilities it exploits.”