Hunting for MiniNt security audit block in registry

Another day in the Advanced Hunting feature.

I was told about a twitter post which explained it’s possible to block Security events from being created.

If the following key is added:
HKLM\System\CurrentControlSet\Control\MiniNt

Event Viewer after the registry key was added and after a reboot

Since it’s registry we have a lot of data to query in the Defender ATP portal (https://securitycenter.windows.com)

The Hunting query will be as follows

// Mattias Borg
// @mattiasborg82
RegistryEvents 
| where (RegistryKey  == "HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Control\\MiniNt") or
        (RegistryKey  == "HKEY_LOCAL_MACHINE\\SYSTEM\\ControlSet001\\Control\\MiniNt")
| sort by EventTime desc
| project EventTime, ComputerName, RegistryKey, InitiatingProcessAccountName, InitiatingProcessCommandLine, InitiatingProcessSHA1

This is the initial hunting query and might be changed to avoid False-Positives if there are any.

To be able to create a custom detection rule we need to add “MachineId” and “ReportId” to the output.

// Mattias Borg
// @mattiasborg82
RegistryEvents 
| where (RegistryKey  == "HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Control\\MiniNt") or
        (RegistryKey  == "HKEY_LOCAL_MACHINE\\SYSTEM\\ControlSet001\\Control\\MiniNt")
| sort by EventTime desc
| project EventTime, ComputerName, RegistryKey, InitiatingProcessAccountName, InitiatingProcessCommandLine, InitiatingProcessSHA1, MachineId, ReportId 

Click on “Create a detection rule”

create detection rule

Fill in the form and select your preferred actions

defender atp custom rule

Happy Hunting!

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