ID | Technique | Tactic |
---|---|---|
T1566.001 | Spearphishing Attachment | Initial Access |
T1566 | Phishing | Initial Access |
Detection: Gsuite Email With Known Abuse Web Service Link
Description
The following analytic detects emails in Gsuite containing links to known abuse web services such as Pastebin, Telegram, and Discord. It leverages Gsuite Gmail logs to identify emails with these specific domains in their links. This activity is significant because these services are commonly used by attackers to deliver malicious payloads. If confirmed malicious, this could lead to the delivery of malware, phishing attacks, or other harmful activities, potentially compromising sensitive information or systems within the organization.
Search
1`gsuite_gmail` "link_domain{}" IN ("*pastebin.com*", "*discord*", "*telegram*","t.me")
2| rex field=source.from_header_address "[^@]+@(?<source_domain>[^@]+)"
3| rex field=destination{}.address "[^@]+@(?<dest_domain>[^@]+)"
4| where not source_domain="internal_test_email.com" and dest_domain="internal_test_email.com"
5| eval phase="plan"
6| eval severity="low"
7|stats values(link_domain{}) as link_domains min(_time) as firstTime max(_time) as lastTime count by is_spam source.address source.from_header_address subject destination{}.address phase severity
8| `security_content_ctime(firstTime)`
9| `security_content_ctime(lastTime)`
10| `gsuite_email_with_known_abuse_web_service_link_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
G Suite Gmail | N/A | 'gsuite:gmail:bigquery' |
'http:gsuite' |
Macros Used
Name | Value |
---|---|
gsuite_gmail | sourcetype=gsuite:gmail:bigquery |
gsuite_email_with_known_abuse_web_service_link_filter | search * |
gsuite_email_with_known_abuse_web_service_link_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 | True |
Implementation
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.
Known False Positives
normal email contains this link that are known application within the organization or network can be catched by this detection.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Suspicious email from $source.address$ to $destination{}.address$ | 25 | 50 | 50 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | http:gsuite |
gsuite:gmail:bigquery |
Integration | ✅ Passing | Dataset | http:gsuite |
gsuite:gmail:bigquery |
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