Try in Splunk Security Cloud

Description

This search looks for AWS CloudTrail events where a user logged into the AWS account, is making API calls and has not enabled Multi Factor authentication. Multi factor authentication adds a layer of security by forcing the users to type a unique authentication code from an approved authentication device when they access AWS websites or services. AWS Best Practices recommend that you enable MFA for privileged IAM users.

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

  • Last Updated: 2018-05-17
  • Author: Bhavin Patel, Splunk
  • ID: 4d46e8bd-4072-48e4-92db-0325889ef894

Annotations

ATT&CK
Kill Chain Phase
  • Exploitation
NIST
  • DE.DP
  • PR.AC
CIS20
  • CIS 16
CVE
1
2
3
4
5
6
7
8
9
`cloudtrail` userIdentity.sessionContext.attributes.mfaAuthenticated=false 
| 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 userIdentity.arn userIdentity.type user 
| `security_content_ctime(firstTime)`  
| `security_content_ctime(lastTime)` 
| `detect_api_activity_from_users_without_mfa_filter`

Macros

The SPL above uses the following Macros:

Note that detect_api_activity_from_users_without_mfa_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
  • userIdentity.sessionContext.attributes.mfaAuthenticated
  • eventName
  • userIdentity.arn
  • userIdentity.type
  • 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. Leverage the support search Create a list of approved AWS service accounts: run it once every 30 days to create a list of service accounts and validate them.
This search produces fields (eventName,userIdentity.type,userIdentity.arn) 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: AWS User ARN, Field: userIdentity.arn\
  3. \
  4. Label: AWS User Type, Field: userIdentity.type
    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

Many service accounts configured within an AWS infrastructure do not have multi factor authentication enabled. Please ignore the service accounts, if triggered and instead add them to the aws_service_accounts.csv file to fine tune the detection. It is also possible that the search detects users in your environment using Single Sign-On systems, since the MFA is not handled by AWS.

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: 1