Officials at the Drupal Association, which operates the sites, said malicious software accessed user information stored on both websites, but Drupal coding and sites running the CMS are unaffected.
The data accessed includes profile information such as username, email address, country, encrypted password, and possibly other as-yet-undetermined details, officials said.
"We are still investigating the incident and may learn about other types of information compromised," association executive director Holly Ross wrote in a May 29 notice on Drupal.org. The bulletin did not indicate when the breach was discovered, when it occurred or how many accounts were hit.
All Drupal.org account passwords were revoked on Wednesday and site users are required to create new passwords the next time they log in. The malware snuck in via a glitch in third-party software that was located on the association's website server, according to officials. They did not name the flawed third-party computer program.
The incident "was not the result of a vulnerability within Drupal itself," Ross emphasized. "We have no evidence to suggest that an unauthorized user modified Drupal core or any contributed projects or packages on Drupal.org."
Open source software is free computer code that developers collaborate on to improve or customize. Drupal.org catalogs Drupal code and contributor projects. Drupal Groups is a social hub that facilitates coding projects among subgroups such as the Drupal4Gov group.
Many federal sites are made with Drupal. Obama administration recommendations on how to build dot-gov sites praise the publishing software for allowing "government agencies all over the world" to collectively develop and share Drupal software enhancements. The how-to manual itself is run by Drupal, as are more than 150 federal sites, including the administration's We the People petition site and Whitehouse.gov, according to the association.
Association officials advised users to reset passwords on any site where they may have created similar passwords. Some older passwords on certain Drupal.org subsites were not strongly encrypted, officials said.
The Drupal sites did not store credit card information. However, as a precaution, officials suggested users closely monitor their financial accounts if they made a transaction on association.drupal.org.
Drupal staff discovered the suspicious activity during a security audit, according to Wednesday’s notice.