This is a whitepaper tutorial that describes steps taken to identify post-authentication remote command execution vulnerabilities in NagiosXI version 5.6.11.
You can download it from the following link: https://packetstormsecurity.com/files/download/157158/nagios5611-exec.txt
Source: https://packetstormsecurity.com/files/157158/NagiosXI-5.6.11-Remote-Command-Execution.html