Error when using shell

[0x076d]

• When I visit the shell URL manually, i have a problem like this
  

• After that, i add this to the URL:
  ?exec_code=Response.Write(new ActiveXObject("WScript.Shell").Exec("cmd.exe /c whoami").StdOut.ReadAll());

But the result is the same..

[Udyz]

i think this is problem... Is your lab running exchange 2016? or you can use this exploit, send mail with malicious pst file via smpt
https://github.com/ktecv2000/ProxyShell

[0x076d]

I use this but drop shell still failed.
But when i use your proxyshell, write file is successfully but can't execute command