The attack utilized a vulnerability in widely used software, with the agencies have "experienced intrusions affecting their MOVEit applications," according to a US government statement. "We are working urgently to understand impacts and ensure timely remediation," Eric Goldstein, a top US cybersecurity official, said.

Initial suspicion has fallen on a Russian-speaking ransomware group, known as CLOP, which has claimed responsibility for a similar ongoing hacking campaign which targeted entities ranging from BBC to British Airways to Shell oil, to schools and hospitals, as well as some US state governments in the Midwest.

CNN reviews of a recent and ongoing hacking campaign as follows: 

But the news adds to a growing tally of victims of a sprawling hacking campaign that began two weeks ago and has hit major US universities and state governments. The hacking spree mounts pressure on federal officials who have pledged to put a dent in the scourge of ransomware attacks that have hobbled schools, hospitals and local governments across the US.