They only worry because the only file they hack was the log file of who look at what, how many time, and for what case
https://www.msn.com/en-us/news/technology/the-fbi-might-have-suffered-a-cyberattack/ar-AA17IURp?ocid

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The FBI might have suffered a cyberattack
Story by Sead Fadilpašić • 5h ago
A cyberattacker seems to have breached the network belonging to the Federal Bureau of Investigation (FBI).