ID | Technique | Tactic |
---|---|---|
T1566 | Phishing | Initial Access |
Detection: Gdrive suspicious file sharing
EXPERIMENTAL DETECTION
This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.
Description
The following analytic identifies suspicious file-sharing activity on Google Drive, where internal users share documents with more than 50 external recipients. It leverages GSuite Drive logs, focusing on changes in user access and filtering for emails outside the organization's domain. This activity is significant as it may indicate compromised accounts or intentional data exfiltration. If confirmed malicious, this behavior could lead to unauthorized access to sensitive information, data leaks, and potential compliance violations.
Search
1`gsuite_drive` name=change_user_access
2| rename parameters.* as *
3| search email = "*@yourdomain.com" target_user != "*@yourdomain.com"
4| stats count values(owner) as owner values(target_user) as target values(doc_type) as doc_type values(doc_title) as doc_title dc(target_user) as distinct_target by src_ip email
5| where distinct_target > 50
6| `gdrive_suspicious_file_sharing_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
N/A | N/A | N/A | N/A | N/A |
Macros Used
Name | Value |
---|---|
gsuite_drive | sourcetype=gsuite:drive:json |
gdrive_suspicious_file_sharing_filter | search * |
gdrive_suspicious_file_sharing_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 |
Implementation
Need to implement Gsuite logging targeting Google suite drive activity. In order for the search to work for your environment please update yourdomain.com
value in the query with the domain relavant for your organization.
Known False Positives
This is an anomaly search, you must specify your domain in the parameters so it either filters outside domains or focus on internal domains. This search may also help investigate compromise of accounts. By looking at for example source ip addresses, document titles and abnormal number of shares and shared target users.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
tbd | 25 | 50 | 50 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | Not Applicable | N/A | N/A | N/A |
Unit | ❌ Failing | N/A | N/A |
N/A |
Integration | ❌ Failing | N/A | N/A |
N/A |
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: 2