THIS IS A EXPERIMENTAL DETECTION
This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.
The following hunting query utilizes a PowerShell Scripted input that captures the bootloader paths for each Windows endpoint it is deployed to. The template inputs.conf is located in the references link. By default, it only captures the path, but may be modified to capture everything that BCDedit provides. It can be verbose, but may be worth it.
- Type: Hunting
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2023-04-14
- Author: Michael Haag, Splunk
- ID: 4f7e3913-4db3-4ccd-afe4-31198982305d
Kill Chain Phase
- CIS 10
1 2 3 4 5 `bootloader_inventory` | stats count min(_time) as firstTime max(_time) as lastTime values(_raw) by host | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_bootloader_inventory_filter`
The SPL above uses the following Macros:
windows_bootloader_inventory_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To implement this analytic, a new stanza will need to be added to a inputs.conf and deployed to all or some Windows endpoints. https://gist.github.com/MHaggis/26518cd2844b0e03de6126660bb45707 provides the stanza. If modifying the sourcetype, be sure to update the Macro for this analytic. Recommend running it daily, or weekly, depending on threat model.
Known False Positives
No false positives here, only bootloaders. Filter as needed or create a lookup as a baseline.
Associated Analytic Story
|81.0||90||90||A list of BootLoaders are present on $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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