This indicates an attack attempt to exploit a Cross-site Request Forgery vulnerability in Nagios Network Analyzer.
The vulnerability is due to insufficient Cross-site Request Forgery protection on the user creation form. An unauthenticated remote attacker could entice an unauthenticated administrator to visit a maliciously crafted webpage to exploit this vulnerability and create a user with administrative privileges on the target server.
Nagios Network Analyzer prior to 2.2.2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the latest update from the vendor.