WASHINGTON, Oct 2 (Reuters) - 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."

(Reporting by Raphael Satter; Editing by Thomas Derpinghaus.)