AWS Excessive Security Scanning

name: AWS Excessive Security Scanning
id: 1fdd164a-def8-4762-83a9-9ffe24e74d5a
version: 10
creation_date: '2021-04-13'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic identifies excessive security scanning activities in AWS by detecting a high number of Describe, List, or Get API calls from a single user. It leverages AWS CloudTrail logs to count distinct event names and flags users with more than 50 such events. This behavior is significant as it may indicate reconnaissance activities by an attacker attempting to map out your AWS environment. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or further exploitation of your cloud infrastructure.
data_source:
    - AWS CloudTrail
search: |-
    `cloudtrail` eventName=Describe* OR eventName=List* OR eventName=Get*
      | fillnull
      | rename user_name as user
      | stats dc(signature) as dc_events min(_time) as firstTime max(_time) as lastTime values(signature) as signature values(dest) as dest values(user_agent) as user_agent values(src) as src values(vendor_account) as vendor_account values(vendor_region) as vendor_region
        BY user
      | where dc_events > 50
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `aws_excessive_security_scanning_filter`
how_to_implement: You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs.
known_false_positives: While this search has no known false positives.
references:
    - https://github.com/aquasecurity/cloudsploit
drilldown_searches:
    - name: View the detection results for - "$user$"
      search: '%original_detection_search% | search  user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | 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"
finding:
    title: User $user$ has excessive number of api calls $dc_events$ from these IP addresses $src$, violating the threshold of 50, using the following actions $signature$.
    entity:
        field: user
        type: user
        score: 50
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - AWS User Monitoring
asset_type: AWS Account
mitre_attack_id:
    - T1526
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: network
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1526/aws_security_scanner/aws_security_scanner.json
          sourcetype: aws:cloudtrail
          source: aws_cloudtrail
      test_type: unit