Detection: Windows Spearphishing Attachment Connect To None MS Office Domain

Updated Date: 2024-10-17 ID: 1cb40e15-cffa-45cc-abbd-e35884a49766 Author: Teoderick Contreras, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies suspicious Office documents that connect to non-Microsoft Office domains. It leverages Sysmon EventCode 22 to detect processes like winword.exe or excel.exe making DNS queries to domains outside of *.office.com or *.office.net. This activity is significant as it may indicate a spearphishing attempt using malicious documents to download or connect to harmful content. If confirmed malicious, this could lead to unauthorized data access, malware infection, or further network compromise.

Search

1`sysmon` EventCode=22 Image IN ("*\\winword.exe","*\\excel.exe","*\\powerpnt.exe","*\\mspub.exe","*\\visio.exe","*\\wordpad.exe","*\\wordview.exe","*\\onenote.exe", "*\\onenotem.exe","*\\onenoteviewer.exe","*\\onenoteim.exe", "*\\msaccess.exe") AND NOT(QueryName IN ("*.office.com", "*.office.net")) 
2| stats count min(_time) as firstTime max(_time) as lastTime by Image QueryName QueryResults QueryStatus Computer 
3| rename Computer as dest 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_spearphishing_attachment_connect_to_none_ms_office_domain_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 22	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_spearphishing_attachment_connect_to_none_ms_office_domain_filter	`search *`

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

KillChainPhase.DELIVERY

NistCategory.DE_AE

Cis18Value.CIS_10

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

Axiom

GOLD SOUTHFIELD

INC Ransom

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 Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line 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

Windows Office document may contain legitimate url link other than MS office Domain. filter is needed

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
a office document process $Image$ connect to an URL link $QueryName$ in $dest$	9	30	30

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

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: 4