Security Related Training & Support Archives

A community member sought assistance with creating a ControlUp trigger or alert to detect when storage devices are added to a physical endpoint and assigned a drive letter or mounted. The data relevant to this event is visible in the ControlUp 4D (CU4D) Performance tab under the Operating System location and stored in the *_devices* index. Specifically, the data is found in the os_disk_configuration field, which contains a JSON array showing details about mounted drives, including drive letters. The user’s challenge was to configure an alert that could detect any newly mounted drive except the system drive C:\ without having to set multiple alerts for every potential drive letter (e.g., D:\, E:\, etc.). They noted the lack of regex support in the filter queries limited their options. The issue arises because the os_disk_configuration field holds a JSON array with multiple drive entries, and filtering out drive_letter "C:\" naively removes all entries due to the structure of the array. Attempts to use a “does not contain” filter eliminated all Windows devices, only showing macOS devices, complicating detection on Windows endpoints. The user also tried to narrow the focus to removable media but learned that their security team's use case requires alerting on any disk, mounted by drive letter, which remains the best indicator available. Advice provided during the discussion included adding filters for platform or OS to ensure the alert targets only Windows devices (e.g., platform set to 1 or OS equals Windows). This helped reduce irrelevant results but did not completely solve the filtering problem. Suggestions included playing with additional filters such as combining conditions to exclude drive_letter "C:\" while explicitly including removable devices, though this required trial and error. A recommendation was to test filter configurations in the CU4D index view, including setting the platform to 1 to target Windows devices specifically. Ultimately, the thread highlights the challenge in using ControlUp’s current filtering capabilities on complex JSON arrays like os_disk_configuration for dynamic drive letters without regex support. The workaround involves narrowing the scope by platform/OS filters and experimenting with composite negation filters, although a straightforward out-of-the-box solution for this specific alert scenario is limited. Users needing comprehensive coverage for any drive letter other than C:\ must create a series of alerts or await enhanced filter features. For now, leveraging the detailed disk configuration data in the *_devices* index with strategic filter layering is the best approach. For further reading on creating and troubleshooting alerts and filters in ControlUp, users can consult official documentation at https://docs.controlup.com and explore ControlUp Academy resources at https://cuacademy.controlup.com.

Read the entire article here...

---