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Description

The following analytic identifies a suspicious outlook.exe process dropped a dll file. This technique was seen in CVE-2024-21378, involves the loading of a custom MAPI form to execute a potentially malicious DLL. Detecting such TTPs serves as a crucial pivot point to identify potential adversaries, malware, or red team activity attempting to leverage this method within phishing campaigns.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-03-20
  • Author: Teoderick Contreras, Splunk
  • ID: fca01769-5163-4b3a-ae44-de874adfc9bc

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.CM
CIS20
  • CIS 10
CVE
ID Summary CVSS
CVE-2024-21378 Microsoft Outlook Remote Code Execution Vulnerability None 


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| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where Processes.process_name=outlook.exe by _time span=1h Processes.process_id Processes.process_name Processes.process Processes.dest Processes.process_guid 
| `drop_dm_object_name(Processes)` 
| join process_guid, _time [ 
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_name ="*.dll" Filesystem.file_path = "*\\AppData\\Local\\Microsoft\\FORMS\\IPM*" by _time span=1h Filesystem.dest Filesystem.file_create_time Filesystem.file_name Filesystem.file_path Filesystem.process_guid 
| `drop_dm_object_name(Filesystem)` 
| fields file_name file_path process_name process_path process dest file_create_time _time process_guid] 
| `windows_phishing_outlook_drop_dll_in_form_dir_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_phishing_outlook_drop_dll_in_form_dir_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
  • dest
  • file_create_time
  • file_name
  • file_path
  • process_name
  • process_path
  • process

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 Filesystem 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

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 an outlook process dropped dll file into $file_path$ 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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