Detection: High Process Termination Frequency

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.

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

Data Source

Name Platform Sourcetype Source
Sysmon EventID 5 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
high_process_termination_frequency_filter search *
high_process_termination_frequency_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1486 Data Encrypted for Impact Impact
KillChainPhase.ACTIONS_ON_OBJECTIVES
NistCategory.DE_AE
Cis18Value.CIS_10
APT38
APT41
Akira
FIN7
FIN8
INC Ransom
Indrik Spider
Magic Hound
Moonstone Sleet
Sandworm Team
Scattered Spider
TA505

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
High frequency process termination (more than 15 processes within 3s) detected on host $dest$ 72 90 80
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Passing N/A N/A N/A
Unit Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

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: GitHub | Version: 5