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Description

The following analytic identifies suspicious PowerShell script that archive files to a temp folder. This anomaly detection serves as a valuable indicator to uncover threats from adversaries utilizing PowerShell scripts for data archiving purposes. Identifying this method becomes pivotal in flagging and investigating potential threats, enabling proactive measures threat actors leveraging similar PowerShell-based data collection and archiving techniques.

  • Type: Anomaly

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-12-19
  • Author: Teoderick Contreras, Splunk
  • ID: 74c5a3b0-27a7-463c-9d00-1a5bb12cb7b5

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1560 Archive Collected Data Collection
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`powershell` EventCode=4104 ScriptBlockText = "*Compress-Archive*"  ScriptBlockText = "*\\Temp\\*" 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID 
| rename Computer as dest 
| rename UserID as user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_archive_collected_data_via_powershell_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_archive_collected_data_via_powershell_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
  • EventCode
  • ScriptBlockText
  • dest
  • user
  • Score

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

powershell may used this function to archive data.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Windows Archive Collected Data via Powershell on $dest$.

:information_source: 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

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