The vBulletin.com forum was not compromised by exploiting a previously unknown vulnerability as a group of hackers claimed, according to vBulletin Solutions, the company that develops the popular Internet forum software.
A hacker group called the Inj3ct0r Team claimed Thursday in a post on Facebook that they used a zero-day exploit -- an exploit for a previously unknown vulnerability -- to compromise the vBulletin.com server and download the user database.
On Friday, vBulletin Solutions reset the password for all forum users and confirmed that attackers broke into its systems and accessed customer IDs and encrypted passwords.
The attackers actually compromised a staging server by exploiting a known issue with the vBulletin "install" directory that customers were informed about several weeks ago, said Wayne Luke, the technical support lead at vBulletin Solutions, Monday via email.
The company warned customers in August to delete the "install" directory from their vBulletin deployments because of a potential exploit vector.
In October, security researchers from Imperva warned that an exploit for that vulnerability was being distributed on hacker websites and allowed attackers to inject rogue administrator accounts into vulnerable vBulletin installations.
Versions 4.2.2 and 5.0.5 of vBulletin fix the security issue, but it's still recommended that customers delete the install directory when not in use, Luke said.
The install directory contains the scripts and files used during the original installation process and during subsequent upgrades.
In addition to deleting the folder, forum owners should also follow several other steps to ensure that their websites have not already been compromised or that they won't be compromised again.
Luke's description of the incident suggests that the compromised staging server had access to production data like customer IDs and encrypted passwords and that vBulletin Solutions forgot to patch the "install" directory issue on its staging server.