The intrusion into the federal judiciary’s case filing system was like “taking candy from a baby,” said one person with knowledge of the hack.

Federal officials are scrambling to assess the damage and address flaws in a sprawling, heavily used computer system long known to have vulnerabilities.

Investigators have uncovered evidence that Russia is at least in part responsible for a recent hack of the computer system that manages U.S. federal court documents, the New York Times reported on Tuesday,