[1] Drupal warns users that runs unpatched installations of version 7 of the popular open source content management system (CMS) may be exposed to vulnerable attacks.
[2] Over 950,000 sites use version 7.x of the CMS that is why these mass SQL injections sites are considered highly critical and dangerous.
[3] The Drupal security team strongly recommends performing backups and also avoiding potential malicious sites.