O365 Threat Intelligence Suspicious File Detected

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Description

The following analytic identifies when a malicious file is detected within the Microsoft Office 365 ecosystem through the Advanced Threat Protection engine. Attackers may stage and execute malicious files from within the Microsoft Office 365 ecosystem. Any detections from built-in Office 365 capabilities should be monitored and responded to appropriately. Certain premium Office 365 capabilities such as Safe Attachment and Safe Links further enhance these detection and response functions.

• Type: TTP

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2024-04-01
• Author: Steven Dick
• ID: 00958c7b-35db-4e7a-ad13-31550a7a7c64

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1204.002	Malicious File	Execution

T1204

User Execution

Execution

Kill Chain Phase

• Installation

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

`o365_management_activity` Workload=ThreatIntelligence Operation=AtpDetection 
| stats values(DetectionMethod) as category  values(FileData.FileName) as file_name values(FileData.FilePath) as file_path values(FileData.FileSize) as file_size values(FileData.MalwareFamily) as signature count, min(_time) as firstTime, max(_time) as lastTime by Id, UserId 
| rename Id as signature_id, UserId as user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `o365_threat_intelligence_suspicious_file_detected_filter`

Macros

The SPL above uses the following Macros:

• o365_management_activity
• security_content_ctime

o365_threat_intelligence_suspicious_file_detected_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
• Workload
• Operation
• Id
• UserId

How To Implement

You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. The threat intelligence workload is typically only visible to E3/E5 level customers.

Known False Positives

unknown

Associated Analytic Story

• Azure Active Directory Account Takeover
• Office 365 Account Takeover
• Ransomware Cloud

RBA

Risk Score	Impact	Confidence	Message
50.0	50	100	Threat Intelligence workload detected a malicious file [$file_name$] from user $user$

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://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/threat-explorer-real-time-detections-about?view=o365-worldwide
• https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-malware-protection-for-spo-odfb-teams-about?view=o365-worldwide

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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