Facebook is usually on the receiving end of legal complaints, but late last month the social media company changed course, filing a civil complaint against NSO Group that alleged the  Israeli cyber company hacked into its WhatsApp servers and tracked specific users.

The NSO Group is one of many companies that operate in the “gray market” of developing and selling hacking technology exclusively to various governments. Lawyers say civil suits against  gray market cyber companies are unusual, and Facebook may run into jurisdictional issues, court splits and a host of other challenges that make prevailing against NSO uncertain.