The security breach suffered by DreamHost in January has resulted in hundreds of rogue PHP pages redirecting users to work-at-home scams, according to researchers from cloud security vendor Zscaler.
DreamHost decided to reset the FTP and shell access passwords for all of its customers after discovering that hackers compromised one of its database servers on January 20.
The company said at the time that no malicious activity had been immediately detected on its customers' accounts, but the situation might have changed in the meantime, according to Zsclaer.
Following the Dreamhost hack many websites hosted by the company have been hijacked to redirect users to a Russian scam page, said Zscaler senior security researcher Julien Sobrier at the end of last week. "I've identified hundreds of websites hosted by DreamHost that contained a PHP page redirecting to hxxp://www.otvetvam.com/."
The landing website promoted a work-at-home scam in Russian. These kind of scams have been around for many years and they usually trick users into buying a so-called starter kit that is supposed to help them earn money on the internet.
"I'm sure this is just the beginning of massive abuses on websites hosted by DreamHost," Sobrier said. However, other web security researchers are not convinced that these attacks are necessarily connected to the DreamHost breach.
Website integrity monitoring firm Sucuri Security has been tracking these attacks and similar ones for a while now and it cannot say whether they started after the DreamHost security breach or that they affect only websites hosted there, said David Dede, a security researcher with the company.
According to Dede, most of the compromised websites analysed by Sucuri had outdated software and other security issues.
Backdoor PHP script
Independent security researcher Denis Sinegubko, who created the Unmask Parasites web scanner, looked at some of the compromised websites given as examples by Zscaler and determined that they all had a backdoor PHP script installed on December 26, long before the DreamHost breach. It might still be an infrastructure-wide compromise though, he said.
Sinegubko was also able to tell who was behind this attack campaign because he'd seen some of the spam domains before. "It's the gang that promotes one of the largest scam campaigns in Russian," the researcher said. "They target themes such as genealogy, horoscopes, medical devices, diets, free downloads, and all other sorts of snake oil."
Regardless of whether these sites were compromised as a result of stolen credentials, vulnerabilities in outdated software or a misconfiguration, webmasters should follow security best practices. These include regularly reviewing the access logs for suspicious activity, checking their web directory trees for any newly created files that look out of place, changing their administrative passwords regularly and keeping their software up to date. Scanning their websites with free services like Zulu, Sucuri or Unmask Parasites, is also recommended.