Top U.S. cybersecurity officials confirmed Thursday that several federal agencies have been impacted by cyberattacks on the widely used MOVEit file transfer tool.

Cybersecurity and Infrastructure Security Agency (CISA) Director Jen Easterly told reporters that her team and the FBI are working to provide assistance to federal agencies that used MOVEit, which is being exploited by the Russia-based Clop ransomware gang in a widespread breach that appears to have compromised dozens of entities.

“We’ve been working closely with Progress Software [which makes MOVEit], the FBI and our federal partners to understand its prevalence within federal agencies,” she said. Earlier in the day, CNN first reported that several government agencies were compromised in the hacks. Easterly said that CISA is providing support to “several agencies that have experienced intrusions of their MOVEit applications.”