Set Default PowerShell Execution Policy To Unrestricted or Bypass
Description
Monitor for changes of the ExecutionPolicy in the registry to the values "unrestricted" or "bypass," which allows the execution of malicious scripts.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-02-18
- Author: Patrick Bareiss, Splunk
- ID: c2590137-0b08-4985-9ec5-6ae23d92f63d
Annotations
ATT&CK
Kill Chain Phase
- Installation
- Actions on Objectives
NIST
- DE.CM
CIS20
- CIS 3
- CIS 8
CVE
Search
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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path=*Software\\Microsoft\\Powershell\\1\\ShellIds\\Microsoft.PowerShell* Registry.registry_value_name=ExecutionPolicy (Registry.registry_value_data=Unrestricted OR Registry.registry_value_data=Bypass) by Registry.registry_path Registry.registry_value_name Registry.registry_value_data Registry.dest
| `drop_dm_object_name(Registry)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `set_default_powershell_execution_policy_to_unrestricted_or_bypass_filter`
Macros
The SPL above uses the following Macros:
set_default_powershell_execution_policy_to_unrestricted_or_bypass_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- Registry.registry_path
- Registry.registry_key_name
- Registry.registry_value_name
- Registry.dest
How To Implement
You must be ingesting data that records process activity from your hosts to populate the Endpoint data model in the Registry node. You must also be ingesting logs with the fields registry_path, registry_key_name, and registry_value_name from your endpoints.
Known False Positives
Administrators may attempt to change the default execution policy on a system for a variety of reasons. However, setting the policy to "unrestricted" or "bypass" as this search is designed to identify, would be unusual. Hits should be reviewed and investigated as appropriate.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
48.0 | 60 | 80 | A registry modification in $registry_path$ with reg key $registry_key_name$ and reg value $registry_value_name$ in host $dest$ |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
Test Dataset
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
source | version: 7