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Description

The following analytic identifies instances where executable files (.exe) are loaded as modules, detected through 'ImageLoaded' events in Sysmon logs. This method leverages Sysmon EventCode 7 to track unusual module loading behavior, which is significant as it deviates from the norm of loading .dll files. This activity is crucial for SOC monitoring because it can indicate the presence of malware like NjRAT, which uses this technique to load malicious modules. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, maintain persistence, and further compromise the host system.

  • Type: TTP

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

  • Last Updated: 2024-05-21
  • Author: Teoderick Contreras, Splunk
  • ID: 3e27af56-fcf0-4113-988d-24969b062be7

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1129 Shared Modules Execution
Kill Chain Phase
  • Installation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


1
2
3
4
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6



`sysmon` EventCode=7 ImageLoaded= *.exe 
| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded Signed SignatureStatus OriginalFileName process_name Computer EventCode ProcessId Hashes IMPHASH 
| rename Computer as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_executable_in_loaded_modules_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_executable_in_loaded_modules_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
  • Image
  • ImageLoaded
  • Signed
  • SignatureStatus
  • OriginalFileName
  • process_name
  • Computer
  • EventCode
  • ProcessId
  • Hashes
  • IMPHASH

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name and imageloaded executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

unknown.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 An executable $ImageLoaded$ loaded by $Image$ 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

source | version: 2