Gsuite Email With Known Abuse Web Service Link

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

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.

name: Gsuite Email With Known Abuse Web Service Link
id: 8630aa22-042b-11ec-af39-acde48001122
version: 10
creation_date: '2021-08-23'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
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.
data_source:
    - G Suite Gmail
search: |-
    `gsuite_gmail` "link_domain{}" IN ("*pastebin.com*", "*discord*", "*telegram*","t.me")
      | rex field=source.from_header_address "[^@]+@(?<source_domain>[^@]+)"
      | rex field=destination{}.address "[^@]+@(?<dest_domain>[^@]+)"
      | where not source_domain="internal_test_email.com" and dest_domain="internal_test_email.com"
      | eval phase="plan"
      | eval severity="low"
      | 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
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `gsuite_email_with_known_abuse_web_service_link_filter`
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.
known_false_positives: normal email contains this link that are known application within the organization or network can be catched by this detection.
references:
    - https://news.sophos.com/en-us/2021/07/22/malware-increasingly-targets-discord-for-abuse/
drilldown_searches:
    - name: View the detection results for - "$destination{}.address$"
      search: '%original_detection_search% | search  destination{}.address = "$destination{}.address$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$destination{}.address$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$destination{}.address$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: destination{}.address
          type: user
          score: 20
          message: Suspicious email from $source.address$ to $destination{}.address$
threat_objects:
    - field: source.address
      type: email_address
analytic_story:
    - Dev Sec Ops
asset_type: GSuite
mitre_attack_id:
    - T1566.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566.001/gsuite_susp_url/gsuite_susp_url.log
          source: http:gsuite
          sourcetype: gsuite:gmail:bigquery
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

9f4c637b-6abf-47c3-b03b-df5329631b2b

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Executable code, not a declarative rule

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