PowerShell Base64 Encoded FromBase64String Cmdlet

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About the rule

Rule Type

Standard

Rule Description

Detects usage of a base64 encoded "FromBase64String" cmdlet in a process command line

Severity

Trouble

Rule Requirement

Criteria

Action1: actionname = "Process started" AND COMMANDLINE contains "OjpGcm9tQmFzZTY0U3RyaW5n,o6RnJvbUJhc2U2NFN0cmluZ,6OkZyb21CYXNlNjRTdHJpbm" OR COMMANDLINE contains "OgA6AEYAcgBvAG0AQgBhAHMAZQA2ADQAUwB0AHIAaQBuAGcA,oAOgBGAHIAbwBtAEIAYQBzAGUANgA0AFMAdAByAGkAbgBnA,6ADoARgByAG8AbQBCAGEAcwBlADYANABTAHQAcgBpAG4AZw" select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME

Detection

Execution Mode

realtime

Log Sources

Windows

Author

Florian Roth (Nextron Systems)