: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.

Try in Splunk Security Cloud

Description

The following analytic identifies the suspicious use of the AWS STS GetSessionToken API call. It leverages CloudWatch logs to detect instances where this API is invoked, focusing on fields such as source IP address, event time, user identity, and status. This activity is significant because attackers can use these tokens to move laterally within the AWS environment and escalate privileges. If confirmed malicious, this could lead to unauthorized access and control over AWS resources, potentially compromising sensitive data and critical infrastructure.

  • Type: Hunting

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

  • Last Updated: 2024-05-14
  • Author: Rod Soto, Splunk
  • ID: 85d7b35f-b8b5-4b01-916f-29b81e7a0551

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1550 Use Alternate Authentication Material Defense Evasion, Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`aws_cloudwatchlogs_eks` ASIA  userIdentity.type=IAMUser
| spath eventName 
| search eventName=GetSessionToken 
| table sourceIPAddress eventTime userIdentity.arn userName userAgent user_type status region 
| `aws_detect_sts_get_session_token_abuse_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_detect_sts_get_session_token_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
  • userIdentity.type
  • eventName
  • sourceIPAddress
  • eventTime
  • userIdentity.arn
  • userName
  • userAgent
  • user_type
  • status
  • region

How To Implement

You must install splunk AWS add-on and Splunk App for AWS. This search works with cloudwatch logs

Known False Positives

Sts:GetSessionToken can be very noisy as in certain environments numerous calls of this type can be executed. This search can be adjusted to provide specific values to identify cases of abuse. In specific environments the use of field requestParameters.serialNumber will need to be used.

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