:warning: THIS IS A EXPERIMENTAL DETECTION

This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.

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Description

The following analytic identifies suspicious use of the AWS STS AssumeRole action. It leverages AWS CloudTrail logs to detect instances where roles are assumed, focusing on specific fields like source IP address, user ARN, and role names. This activity is significant because attackers can use assumed roles to move laterally within the AWS environment and escalate privileges. If confirmed malicious, this could allow attackers to gain unauthorized access to sensitive resources, execute code, or further entrench themselves within the environment, leading to potential data breaches or service disruptions.

  • Type: Hunting

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

  • Last Updated: 2024-05-20
  • Author: Rod Soto, Splunk
  • ID: 8e565314-b6a2-46d8-9f05-1a34a176a662

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1078 Valid Accounts Defense Evasion, Persistence, Privilege Escalation, Initial Access
Kill Chain Phase
  • Exploitation
  • Installation
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


1
2
3



`cloudtrail` user_type=AssumedRole userIdentity.sessionContext.sessionIssuer.type=Role 
| table sourceIPAddress userIdentity.arn user_agent user_access_key status action requestParameters.roleName responseElements.role.roleName responseElements.role.createDate 
| `aws_detect_sts_assume_role_abuse_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_detect_sts_assume_role_abuse_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • user_type
  • userIdentity.sessionContext.sessionIssuer.type
  • sourceIPAddress
  • userIdentity.arn
  • user_agent
  • user_access_key
  • status
  • action
  • requestParameters.roleName
  • esponseElements.role.roleName
  • esponseElements.role.createDate

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

Sts:AssumeRole can be very noisy as it is a standard mechanism to provide cross account and cross resources access. This search can be adjusted to provide specific values to identify cases of abuse.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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