Certified Pre-Owned - backup of CA private key - rule 1

Original query, unchanged.

SecurityEvent
// Fill in the machine name of your CA.
| where EventID == 5058 and Computer contains "<YOUR CA MACHINE NAME>"
| where EventData contains "%%2499" // Machine key.
| extend EventData=parse_xml(EventData)
| mv-apply d=EventData.EventData.Data on
(
    where d["@Name"]=="KeyName"
    | project KeyName=tostring(d["#text"])
)
| mv-apply d=EventData.EventData.Data on
(
    where d["@Name"]=="SubjectUserName"
    | project SubjectUserName=tostring(d["#text"])
)
| mv-apply d=EventData.EventData.Data on
(
    where d["@Name"]=="Operation"
    | project Operation=tostring(d["#text"])
)
| extend Operation=iff(Operation == "%%2458", "Read persisted key from file", Operation)
// This one is a guess and very poorly documented :(
| extend Operation=iff(Operation == "%%2459", "Write persisted key to file", Operation)
// Fill in the keyname of the CA key.
| where KeyName == "<INSERT ISSUING CA KEY HERE>" // Or any other key you want to monitor.