Website administration firm cPanel has told The Reg that one of its proxy servers was hacked, potentially exposing customers' administrator-level passwords.
cPanel discovered that one of its systems, used to handle technical support tickets, was infiltrated nearly a week ago.
The biz, which provides tools for managing Unix-powered websites, has urged anyone who contacted its help-desk within the last six months to change their root passwords - a credential requested in new support tickets. It is understood this information is needed to allow cPanel employees to access bamboozled customers' web servers.
"If you are using an unprivileged account with 'sudo' or 'su' for root logins, we recommend you change the account password. Even if you are using ssh keys we still recommend rotating keys on a regular basis," the company said in an email.
The biz discovered that a proxy server was hacked by "a malicious third party" through a compromised workstation used by one of its support bods.
"Only a small group of our technical analysts used this particular machine for logins, which means that fortunately only some customers who opened a ticket in the past six months would be affected by this compromise," cPanel said.
It added that there was no evidence that any other sensitive data was exposed, but said the investigation was ongoing.
The company is introducing new processes to stop a similar attack in the future, including changing how servers are accessed, providing unique SSH keys for each new support ticket, and generating single-use username and password credentials for the WebHost Manager that are only valid while staff are logged into customers' servers.
"It is now possible for our technical analysts to service your support requests without you providing your server's password for nearly all requests involving machines running our cPanel and WHM product," the firm said.
Ultimately, cPanel hopes to get rid of the need for analysts to require customers' superuser passwords, and are testing a solution for that now.
The digital break-in follows the news that help-desk provider Zendesk was hacked last week. Intruders got their hands on email addresses for users of Twitter, Pinterest and Tumblr along with support message subject lines. ®