Lawmakers were quietly briefed on the hack last month and are now seeking more information on the fallout. 

The federal judiciary said it is “taking additional steps to strengthen protections for sensitive case documents” in response to the attacks.

The Administrative Office of the U.S. courts said Thursday it was adopting additional security measures to protect its electronic case filing system in response to recent cyberattacks that may have exposed sensitive information.

POLITICO first reported Wednesday that the electronic case filing system used by the federal courts were compromised in a widespread hacking effort across several U.S. states. The incident affected the judiciary’s federal core case management system, which includes the Case Management/Electronic Case Files, or CM/ECF, which legal professionals use to upload and manage case documents; and PACER, a system that provides some public access to the same data.

In a release posted Thursday, the federal judiciary said it is “taking additional steps to strengthen protections for sensitive case documents in response to recent escalated cyberattacks of a sophisticated and persistent nature on its case management system.”

“The Judiciary is also further enhancing security of the system and to block future attacks, and it is prioritizing working with courts to mitigate the impact on litigants,” the statement added.

A spokesperson for the Senate Judiciary Committee, granted anonymity because they were not authorized to speak publicly about the attacks, said that the Senate and House Judiciary Committees, along with representatives from the House and Senate Appropriations Committees and the Senate Judiciary Subcommittee on Federal Courts, received a briefing about the attacks on July 23.

The spokesperson added that the committees had requested a classified follow-up briefing in September once Congress returns from its August recess.

It is not immediately clear whether state-sponsored actors or criminal groups are behind the breaches or how they were able to access the federal court filing system.

A person familiar with the attacks, granted anonymity as they were not authorized to speak publicly, said they bore similar hallmarks to a data breach of the U.S. federal courts system dating to early 2020. “The central issue is similar and/or related to vulnerabilities exploited during the 2020 hack,” the person said.

The Justice Department opened an investigation into the attack in July 2022. At the time, then-House Judiciary Committee Chair Jerrold Nadler (D-N.Y.) told fellow lawmakers that “three hostile foreign actors” were linked to the incident.

House Judiciary Committee Ranking Member Jamie Raskin (D-Md.) said the most recent hack of the federal court filing system “underscores the urgent need for Congress to fund the judiciary at its requested levels so they can modernize their infrastructure and protect the integrity of our legal system.”

“Judges and other experts have long warned Congress that the federal judiciary’s outdated electronic systems are vulnerable to exactly this kind of breach,” Raskin said. “We can’t allow sensitive information to remain exposed to such serious and entirely preventable threats.”

The chief justices of federal courts in the 8th Circuit — including Arkansas, Iowa, Minnesota, Missouri, Nebraska, North Dakota and South Dakota — were briefed on the most recent breaches last week during a conference in Kansas City.

The U.S. Courts noted that the Judiciary is working with the Department of Homeland Security and the Justice Department on responding to the breaches, alongside other executive agencies and with Congress.

A spokesperson for the DOJ declined to comment, while a spokesperson for DHS did not respond to a request for comment.