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Description

This search is to detect a shared file in google drive with suspicious file name that are commonly used by spear phishing campaign. This technique is very popular to lure the user by running a malicious document or click a malicious link within the shared file that will redirected to malicious website. This detection can also catch some normal email communication between organization and its external customer.

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

  • Last Updated: 2021-08-23
  • Author: Teoderick Contreras, Splunk
  • ID: 07eed200-03f5-11ec-98fb-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1566.001 Spearphishing Attachment Initial Access
T1566 Phishing Initial Access
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
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`gsuite_drive` parameters.owner_is_team_drive=false "parameters.doc_title" IN ("*dhl*", "* ups *", "*delivery*", "*parcel*", "*label*", "*invoice*", "*postal*", "*fedex*", "* usps *", "* express *", "*shipment*", "*Banking/Tax*","*shipment*", "*new order*") parameters.doc_type IN ("document","pdf", "msexcel", "msword", "spreadsheet", "presentation") 
| rex field=parameters.owner "[^@]+@(?<source_domain>[^@]+)" 
| rex field=parameters.target_user "[^@]+@(?<dest_domain>[^@]+)" 
| where not source_domain="internal_test_email.com" and dest_domain="internal_test_email.com" 
| eval phase="plan" 
| eval severity="low" 
| stats count min(_time) as firstTime max(_time) as lastTime by email parameters.owner parameters.target_user parameters.doc_title parameters.doc_type phase severity 
| rename parameters.target_user AS user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `gsuite_suspicious_shared_file_name_filter`

Macros

The SPL above uses the following Macros:

Note that gsuite_suspicious_shared_file_name_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • parameters.doc_title
  • src_domain
  • dest_domain
  • email
  • parameters.visibility
  • parameters.owner
  • parameters.doc_type

How To Implement

To successfully implement this search, you need to be ingesting logs related to gsuite having the file attachment metadata like file type, file extension, source email, destination email, num of attachment and etc. In order for the search to work for your environment, please edit the query to use your company specific email domain instead of internal_test_email.com.

Known False Positives

normal user or normal transaction may contain the subject and file type attachment that this detection try to search

Associated Analytic story

RBA

Risk Score Impact Confidence Message
21.0 30 70 suspicious share gdrive from $parameters.owner$ to $email$ namely as $parameters.doc_title$

Reference

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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