Ukrainian hackers stole technical documentation on 500 Russian Ministry of Defense facilities, according to Ukrainian public broadcaster Suspilne, referring to its sources in the Security Service of Ukraine (SBU).

“Hackers of the Blackjack group, which is likely affiliated with the SBU, hacked into a Russian state-owned company that builds military facilities throughout Russia. Ukrainian cyber warriors downloaded over 1.2 TB of data from the ‘Main Military Construction Directorate for Special Facilities’,” Suspilne wrote.

This included over 500 datasheets on Russian Ministry of Defense military facilities: weapon arsenals, anti-aircraft missile sites, headquarters, barracks, including those located in Ukrainian territories occupied by the enemy, as well as other technical project documentation, according to the sources.

Suspilne says the hackers also took down seven servers and encrypted over 150 employee computers at the agency.

“Effectively, the Russian construction specialists were left without any data or backup copies of information,” Suspilne wrote.