Detection: O365 Safe Links Detection

Updated Date: 2024-11-14 ID: 711d9e8c-2cb0-45cf-8813-5f191ecb9b26 Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects when any Microsoft Safe Links alerting is triggered. This behavior may indicate when user has interacted with a phishing or otherwise malicious link within the Microsoft Office ecosystem.

Search

1`o365_management_activity` Name="*a potentially malicious URL*" Operation=AlertEntityGenerated 
2| fromjson Data 
3| stats count min(_time) as firstTime max(_time) as lastTime values(ObjectId) as url values(od) as desc by AlertId,trc,Operation,Name,ot 
4| rename Name as signature, AlertId as signature_id, trc as user,ot as action 
5| eval action = CASE(action == "Allowed", "allowed", action=="BlockPageOverride", "allowed", true(),"blocked") 
6| `security_content_ctime(firstTime)` 
7| `security_content_ctime(lastTime)` 
8| `o365_safe_links_detection_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name	Value
o365_management_activity	`sourcetype=o365:management:activity`
o365_safe_links_detection_filter	`search *`

o365_safe_links_detection_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

Delivery

DE.CM

CIS 10

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

You must install the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. The Safe Links capability must be configured and is typically only available to E3/E5 level customers.

Known False Positives

Based on Safe Links policies, may vary.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

$user$ triggered a Microsoft Safe Links detection.

Risk Object	Risk Object Type	Risk Score	Threat Objects
user	user	40	url

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`o365`	`o365:management:activity`
Integration	✅ Passing	Dataset	`o365`	`o365:management:activity`

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: 3