ID | Technique | Tactic |
---|---|---|
T1566 | Phishing | Initial Access |
Detection: Windows Phishing Outlook Drop Dll In FORM Dir
Description
The following analytic detects the creation of a DLL file by an outlook.exe process in the AppData\Local\Microsoft\FORMS directory. This detection leverages data from the Endpoint.Processes and Endpoint.Filesystem datamodels, focusing on process and file creation events. This activity is significant as it may indicate an attempt to exploit CVE-2024-21378, where a custom MAPI form loads a potentially malicious DLL. If confirmed malicious, this could allow an attacker to execute arbitrary code, leading to further system compromise or data exfiltration.
Search
1
2| 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
3| `drop_dm_object_name(Processes)`
4| join process_guid, _time [
5| 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
6| `drop_dm_object_name(Filesystem)`
7| fields file_name file_path process_name process_path process dest file_create_time _time process_guid]
8| `windows_phishing_outlook_drop_dll_in_form_dir_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Sysmon EventID 11 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_summariesonly | summariesonly= summariesonly_config allow_old_summaries= oldsummaries_config fillnull_value= fillnull_config`` |
windows_phishing_outlook_drop_dll_in_form_dir_filter | search * |
windows_phishing_outlook_drop_dll_in_form_dir_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
an outlook process dropped dll file into $file_path$ on $dest$ | 49 | 70 | 70 |
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: 2