Malicious PowerShell Process With Obfuscation Techniques
Description
This search looks for PowerShell processes launched with arguments that have characters indicative of obfuscation on the command-line.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-01-19
- Author: David Dorsey, Splunk
- ID: cde75cf6-3c7a-4dd6-af01-27cdb4511fd4
Annotations
ATT&CK
Kill Chain Phase
- Command & Control
- Actions on Objectives
NIST
- PR.PT
- DE.CM
- PR.IP
CIS20
- CIS 3
- CIS 7
- CIS 8
CVE
Search
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| tstats `security_content_summariesonly` count values(Processes.process) as process values(Processes.parent_process) as parent_process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` by Processes.user Processes.process_name Processes.original_file_name Processes.parent_process_name Processes.dest Processes.process
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| eval num_obfuscation = (mvcount(split(process,"`"))-1) + (mvcount(split(process, "^"))-1) + (mvcount(split(process, "'"))-1)
| `malicious_powershell_process_with_obfuscation_techniques_filter`
| search num_obfuscation > 10
Macros
The SPL above uses the following Macros:
malicious_powershell_process_with_obfuscation_techniques_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Supported Add-on (TA)
List of Splunk Add-on’s tested to work with the analytic.
Required fields
List of fields required to use this analytic.
- _time
- Processes.dest
- Processes.user
- Processes.parent_process_name
- Processes.parent_process
- Processes.original_file_name
- Processes.process_name
- Processes.process
- Processes.process_id
- Processes.parent_process_path
- Processes.process_path
- Processes.parent_process_id
How To Implement
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint
datamodel in the Processes
node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.
Known False Positives
These characters might be legitimately on the command-line, but it is not common.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
42.0 | 70 | 60 | Powershell.exe running with potential obfuscated arguments 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.
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: 5