legitimate device registrations may coincidentally use the `10.0.19041.928` build (windows 10 20h1) with a default `desktop-` hostname, particularly on imaged or unmanaged windows hosts that have not been updated. validate against your device inventory, expected provisioning workflows, and the registering user before escalating.

Techniques

T1098

Sample rules

Entra ID Device Registration with ROADtools Default OS Build

source: elastic
technicques:
- T1098

Description

Identifies a Microsoft Entra ID device registration where the recorded cloud device operating system build is “10.0.19041.928” and the device display name follows the default “DESKTOP-” pattern. This combination is the default device profile that ROADtools (roadtx) uses when registering a device, and it is uncommon for the OS build to match the hardcoded value across an environment of otherwise patched hosts. Adversaries register rogue devices in Entra ID to acquire a Primary Refresh Token (PRT), establish persistence, and obtain trusted, programmatic access to the tenant. Because the OS build is a tool default, this is a high-fidelity but evadable indicator; baseline approved provisioning tooling and device naming conventions before relying on it.

Detection logic

data_stream.dataset:"azure.auditlogs" and event.action:"Add device" and
    azure.auditlogs.properties.target_resources.0.modified_properties.3.new_value:*10.0.19041.928* and
    azure.auditlogs.properties.target_resources.0.modified_properties.4.new_value:*DESKTOP-*