Los Angeles-based Web hosting firm DreamHost reset the FTP and shell access passwords for all of its customers on Friday after detecting unauthorized activity within one of its databases.
"One of DreamHost's database servers was illegally accessed using an exploit that was not previously known or prevented by our layered security systems in place," said DreamHost's CEO, Simon Anderson, in a blog post on Saturday.
Even though it couldn't be blocked, the unauthorized access was detected by one of the company's intrusion detection systems (IDS), allowing its security team to react quickly and take the necessary mitigation steps.
The company notified its customers about the security breach via email and informed them that only passwords used for FTP and shell access were affected by the breach. Billing or personal information was not exposed, DreamHost said.
DreamHost customers use three different passwords for accessing the Web administration panel, their email and their FTP/shell accounts. Changing the email passwords was also recommended by the company as a precaution, but this wasn't enforced.
DreamHost's staff worked throughout Friday to reset all FTP passwords for shared hosting accounts, leading to some situations where customers changed their passwords on their own after hearing about the incident only to have them reset later in the day by the company.
Due to the large number of people attempting to change their passwords, the Web administration panel became unresponsive for limited periods of time.
The whole password reset operation was finalized Friday evening for shared hosting customers and Saturday for VPS (virtual private server) customers. DreamHost claims to have over 300,000 customers worldwide.
"Due to the fast action we took to reset passwords, we're not seeing any unusual malicious activity on customer accounts," DreamHost said via its status page on Sunday. "Our security software and systems are functioning normally."
The company will continue to monitor customer accounts and their Web properties for unusual and potentially malicious activity that might be a result of this incident. "We'll all be working hard over the coming days to minimize any impact on customers beyond the password reset," Anderson said.
Some DreamHost customers complained in replies to the company's announcement that their websites were recently infected with malware. However, website integrity monitoring firm Sucuri Security said that those infections seem unrelated to this incident.
"We have cleaned quite a few of these websites, and most of them were infected through outdated software installed by the customer," Sucuri security researcher David Dede said in a blog post. "The important note to take here is it's crucially important to ensure you're keeping your sites updated."
DreamHost customers should also change their passwords on other websites where they might have used them and should be on the lookout for potential phishing emails sent by hackers in the company's name.