splunk-security_content/docs/_posts/2021-04-13-office_application_spawn_rundll32_process.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Office Application Spawn rundll32 process	Phishing , Spearphishing Attachment	Endpoint	2021-04-13	true		Phishing Spearphishing Attachment Initial Access Initial Access Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

this detection was designed to identifies suspicious spawned process of known MS office application due to macro or malicious code. this technique can be seen in so many malware like trickbot that used MS office as its weapon or attack vector to initially infect the machines.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint- Datasource: Splunk Add-on for Sysmon
• Last Updated: 2021-04-13
• Author: Teoderick Contreras, Splunk
• ID: 958751e4-9c5f-11eb-b103-acde48001122

Annotations

ATT&CK

ID	Technique	Tactic
T1566	Phishing	Initial Access

| T1566.001 | Spearphishing Attachment | Initial Access |

Kill Chain Phase

• Exploitation

NIST

CIS20

CVE

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.parent_process_name = "winword.exe" OR Processes.parent_process_name = "excel.exe" OR Processes.parent_process_name = "powerpnt.exe") AND `process_rundll32` by Processes.parent_process Processes.process_name Processes.process_id Processes.process_guid Processes.process Processes.user Processes.dest 
| `drop_dm_object_name("Processes")` 
| `security_content_ctime(firstTime)` 
|`security_content_ctime(lastTime)` 
| `office_application_spawn_rundll32_process_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• process_rundll32
• security_content_summariesonly

ℹ️ office_application_spawn_rundll32_process_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

• Processes.dest
• Processes.user
• Processes.parent_process_name
• Processes.parent_process
• Processes.original_file_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_path
• Processes.process_path
• Processes.parent_process_id

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 Processes 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

• Spearphishing Attachments
• Trickbot
• IcedID

RBA

Risk Score	Impact	Confidence	Message
63.0	70	90	Office application spawning rundll32.exe on dest

ℹ️ 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

• https://any.run/malware-trends/trickbot
• https://any.run/report/47561b4e949041eff0a0f4693c59c81726591779fe21183ae9185b5eb6a69847/aba3722a-b373-4dae-8273-8730fb40cdbe

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566.001/datasets/windows-sysmon.log

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