A hacking group has compromised at least nine global organizations in the fields of technology, defense, energy, and other key sectors as part of an apparent espionage campaign, a U.S. cybersecurity group has claimed.

Cybersecurity firm Palo Alto Networks said in a report published Sunday that in the U.S. alone, hundreds of organizations were targeted by hackers as part of an espionage effort that took place between late September and early October.

The hacking group compromised “at least nine global entities across the technology, defense, healthcare, energy, and education industries,” it said.

“Through global telemetry, we believe that the actor targeted at least 370 Zoho [software] … in the United States alone,” Palo Alto Networks said in its report. “Given the scale, we assess that these scans were largely indiscriminate in nature as targets ranged from education to Department of Defense entities.”

The hacking group was able to compromise the entities by exploiting vulnerabilities in software used to manage network passwords, known as ManageEngine ADSelfService Plus, the post said.

“Ultimately, the actor was interested in stealing credentials, maintaining access, and gathering sensitive files from victim networks for exfiltration,” Palo Alto Networks noted.