Oracle says hackers are trying to extort its customers

Oracle said on Thursday that customers of its E-Business Suite of products "have received extortion emails," confirming a warning first issued on Wednesday by Alphabet's Google.

In a blog post, the California-based tech company said its investigation found that hackers had made potential use of previously identified software vulnerabilities and urged customers to upgrade their products. Oracle did not immediately respond when asked how many clients were affected. Google has described the hacking campaign as "high volume," but declined to go into detail.

Cynthia Kaiser, the head of cybersecurity firm Halcyon's Ransomware Research Center, previously told Reuters that her company had seen extortion demands ranging from millions to tens of millions of dollars, with the highest coming in at $50 million.

In a message to Reuters, the ransomware group tied by Google to the extortion campaign, cl0p, said Oracle had "bugged up," but added: "We not prepared to discuss details at this time."

The group's members and location are not publicly known. But security researchers have long identified the group as Russia-linked or Russian-speaking. It is a ransomware-as-a-service group, meaning that it hires out its software and infrastructure for other cybercriminals in return for a cut of the proceeds.

Japanese cybersecurity firm Trend Micro previously described cl0p as "a trendsetter for its ever-changing tactics."