For website admins, we recommend the deletion of the files resembling those described above, and the updating of their content management systems – especially WordPress, Joomla or Drupal. More information on this threat, as well as the other components that need to be taken note of are available in our paper, Stealrat: An In-Depth Look at an Emerging Spambot.
Обновить CMS. А для уменьшения последствий эксплуатации будущих дырок перевести сайт на систему управления версиями, например git. Позволит откатывать сайт.