US authorities expressed increased alarm Thursday about an intrusion into computer systems around the globe that officials suspect was carried out by Russian hackers, with the nation’s civilian cybersecurity agency warning that it poses a “grave” risk to government and private networks.
The Cybersecurity and Infrastructure Security Agency said in its most detailed comments yet that the intrusion has compromised government agencies as well as “critical infrastructure” in a sophisticated attack that was hard to detect and will be difficult to undo.
CISA did not say which agencies or infrastructure were breached or what information taken in an attack that it previously said appeared to have begun in March.
“This threat actor has demonstrated sophistication and complex tradecraft in these intrusions,” the agency said in an unusual alert. “CISA expects that removing the threat actor from compromised environments will be highly complex and challenging.”
The agency previously said that the perpetrators had used network management software from Texas-based SolarWinds t o infiltrate computer networks. Its new alert said the attackers may have used other methods as well.
A US official previously told The Associated Press that Russia-based hackers are suspected, but neither CISA nor the FBI has publicly said who is believed be responsible.
Another US official, speaking Thursday on condition of anonymity to discuss a matter that is under investigation, said the hack was severe and extremely damaging although the Trump administration was not yet ready to publicly blame anyone for it.
“This is looking like it’s the worst hacking case in the history of America,” the official said. “They got into everything.”
The official said the administration is working on the assumption that most, if not all, government agencies were compromised but the extent of the damage was not yet known.
Asked whether Russia was behind the attack, the official said: “We believe so. We haven’t said that publicly yet because it isn’t 100 percent confirmed.”