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Description

The following analytic identifies a high frequency of process termination events on a computer within a short period. It leverages Sysmon EventCode 5 logs to detect instances where 15 or more processes are terminated within a 3-second window. This behavior is significant as it is commonly associated with ransomware attempting to avoid exceptions during file encryption. If confirmed malicious, this activity could indicate an active ransomware attack, potentially leading to widespread file encryption and significant data loss.

  • Type: Anomaly

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

  • Last Updated: 2024-08-14
  • Author: Teoderick Contreras
  • ID: 17cd75b2-8666-11eb-9ab4-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1486 Data Encrypted for Impact Impact
Kill Chain Phase
  • Actions On Objectives
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


1
2
3
4
5
6
7



`sysmon` EventCode=5 
|bin _time span=3s 
|stats values(Image) as proc_terminated min(_time) as firstTime max(_time) as lastTime  count by _time dest EventCode ProcessID 
| where count >= 15 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| `high_process_termination_frequency_filter`

Macros

The SPL above uses the following Macros:

:information_source: high_process_termination_frequency_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.

  • EventCode
  • Image
  • dest
  • _time
  • ProcessID

How To Implement

To successfully implement this search, you need to be ingesting logs with the Image (process full path of terminated process) from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

admin or user tool that can terminate multiple process.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
72.0 90 80 High frequency process termination (more than 15 processes within 3s) detected on host $dest$

: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

source | version: 4