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Description

This search looks for successful AWS CloudTrail activity by user accounts that are not listed in the identity table or aws_service_accounts.csv. It returns event names and count, as well as the first and last time a specific user or service is detected, grouped by users. Deprecated because managing this list can be quite hard.

  • Type: Hunting

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

  • Last Updated: 2020-07-21
  • Author: Bhavin Patel, Splunk
  • ID: ada0f478-84a8-4641-a3f1-d82362d4bd55

Annotations

ATT&CK
ID Technique Tactic
T1078.004 Cloud Accounts Defense Evasion, Initial Access, Persistence, Privilege Escalation
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.DP
  • DE.CM
  • PR.AC
  • ID.AM
CIS20
  • CIS 16
CVE 
1
2
3
4
5
6
7
8
9
10
11
12
13

`cloudtrail` errorCode=success 
| rename userName as identity 
| search NOT [
| inputlookup identity_lookup_expanded 
| fields identity] 
| search NOT [
| inputlookup aws_service_accounts 
| fields identity] 
| rename identity as user 
| stats count min(_time) as firstTime max(_time) as lastTime values(eventName) as eventName by user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_aws_api_activities_from_unapproved_accounts_filter`

Macros

The SPL above uses the following Macros:

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

Lookups

The SPL above uses the following Lookups:

Required field

  • _time
  • errorCode
  • userName
  • eventName
  • user

How To Implement

You must install the AWS App for Splunk (version 5.1.0 or later) and Splunk Add-on for AWS (version 4.4.0 or later), then configure your AWS CloudTrail inputs. You must also populate the identity_lookup_expanded lookup shipped with the Asset and Identity framework to be able to look up users in your identity table in Enterprise Security (ES). Leverage the support search called “Create a list of approved AWS service accounts”: run it once every 30 days to create and validate a list of service accounts.
This search produces fields (eventName,firstTime,lastTime) that are not yet supported by ES Incident Review and therefore cannot be viewed when a notable event is raised. These fields contribute additional context to the notable. To see the additional metadata, add the following fields, if not already present, to Incident Review - Event Attributes (Configure > Incident Management > Incident Review Settings > Add New Entry):\n1. Label: AWS Event Name, Field: eventName\

  1. \
  2. Label: First Time, Field: firstTime\
  3. \
  4. Label: Last Time, Field: lastTime
    Detailed documentation on how to create a new field within Incident Review may be found here: https://docs.splunk.com/Documentation/ES/5.3.0/Admin/Customizenotables#Add_a_field_to_the_notable_event_details

Known False Positives

It’s likely that you’ll find activity detected by users/service accounts that are not listed in the identity_lookup_expanded or ` aws_service_accounts.csv file. If the user is a legitimate service account, update the aws_service_accounts.csv` table with that entry.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

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

source | version: 2