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 you add CurrentControlSetControlMiniNt key, the Windows will think it is WinPE and will not log any event to the Security Log 😱#hacked #windowsinternals #redteam
— Grzegorz Tworek (@0gtweet) October 11, 2019

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”