"Recently the Drupal Security Team has seen a trend of attacks utilizing a site mis-configuration. This issue only affects sites that allow file uploads by non-trusted or anonymous visitors, and stores those uploads in a public file system. These files are publically accessible allowing attackers to point search engines and people directly to them on the site. The majority of the reports are based around the webform module, however, other modules are vulnerable to this misconfiguration as well."
url:
https://www.drupal.org/psa-2016-003
261