The U.S. Justice Department says the Russian hackers behind the massive SolarWinds cyberespionage campaign broke into the email accounts of some of the most prominent federal prosecutors' offices in the United States during 2020.

The Justice Department said 80 percent of the Microsoft e-mail accounts used by employees in the four U.S. attorney offices in New York were breached.

Altogether, the Justice Department said the e-mail account of at least one employee in 27 U.S. attorney offices were compromised during the Russian hacking campaign.

In a statement on July 30, the Justice Department said it believes the accounts were compromised from May 7 to December 27.

That time frame is notable because the SolarWinds campaign was first discovered and publicized in mid-December.

The Russian hacking scheme infiltrated dozens of private-sector companies and think tanks as well as at least nine U.S. government agencies.

In April, the administration of President Joe Biden announced sanctions in response to the SolarWinds hack and Russian efforts to interfere in the 2020 U.S. presidential election.

The punitive measures included the expulsion of Russian diplomats from the United States.

Russia has denied any wrongdoing.

The Administrative Office of U.S. Courts confirmed in January that it was also breached.

That gave the SolarWinds hackers another entry point to steal confidential information like trade secrets, espionage targets, whistle-blower reports, and arrest warrants.

The list of affected offices include several large and high-profile ones like those in Los Angeles, Miami, Washington, and the Eastern District of Virginia.

The Southern and Eastern districts of New York, where large numbers of staff were hit, handle some of the most prominent prosecutions in the country.

Based on reporting by AP

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