Detection: Winword Spawning Cmd

Updated Date: 2024-09-30 ID: 6fcbaedc-a37b-11eb-956b-acde48001122 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies instances where Microsoft Word (winword.exe) spawns the command prompt (cmd.exe). This behavior is detected using Endpoint Detection and Response (EDR) telemetry, focusing on process creation events where the parent process is winword.exe. This activity is significant because it is uncommon and often associated with spearphishing attacks, where malicious attachments execute commands via cmd.exe. If confirmed malicious, this could allow an attacker to execute arbitrary commands, potentially leading to further system compromise, data exfiltration, or lateral movement within the network.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=winword.exe `process_cmd` by 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_id 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `winword_spawning_cmd_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	`'crowdstrike:events:sensor'`	`'crowdstrike'`
Sysmon EventID 1	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Windows Event Log Security 4688	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`

Macros Used

Name	Value
process_cmd	`(Processes.process_name=cmd.exe OR Processes.original_file_name=Cmd.Exe)`
winword_spawning_cmd_filter	`search *`

winword_spawning_cmd_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
T1566	Phishing	Initial Access
T1566.001	Spearphishing Attachment	Initial Access

KillChainPhase.DELIVERY

NistCategory.DE_CM

Cis18Value.CIS_10

Axiom

GOLD SOUTHFIELD

INC Ransom

APT-C-36

APT1

APT12

APT19

APT28

APT29

APT30

APT32

APT33

APT37

APT38

APT39

APT41

Ajax Security Team

Andariel

BITTER

BRONZE BUTLER

BlackTech

CURIUM

Cobalt Group

Confucius

DarkHydrus

Darkhotel

Dragonfly

EXOTIC LILY

Elderwood

FIN4

FIN6

FIN7

FIN8

Ferocious Kitten

Gallmaker

Gamaredon Group

Gorgon Group

Higaisa

Inception

IndigoZebra

Kimsuky

Lazarus Group

LazyScripter

Leviathan

Machete

Malteiro

Mofang

Molerats

Moonstone Sleet

MuddyWater

Mustang Panda

Naikon

Nomadic Octopus

OilRig

PLATINUM

Patchwork

RTM

Rancor

RedCurl

Saint Bear

Sandworm Team

SideCopy

Sidewinder

Silence

Star Blizzard

TA2541

TA459

TA505

TA551

The White Company

Threat Group-3390

Tonto Team

Transparent Tribe

Tropic Trooper

WIRTE

Windshift

Winter Vivern

Wizard Spider

admin@338

menuPass

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

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

False positives should be limited, but if any are present, filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
$parent_process_name$ on $dest$ by $user$ launched command: $process_name$ which is very common in spearphishing attacks.	70	70	100

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

https://app.any.run/tasks/73af0064-a785-4c0a-ab0d-cde593fe16ef/

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