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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.

  • Type: TTP

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

  • Last Updated: 2024-05-08
  • Author: Patrick Bareiss, Splunk
  • ID: 1fdd164a-def8-4762-83a9-9ffe24e74d5a

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1526 Cloud Service Discovery Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 13
CVE 


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`cloudtrail` eventName=Describe* OR eventName=List* OR eventName=Get*  
| stats dc(eventName) as dc_events min(_time) as firstTime max(_time) as lastTime values(eventName) as command values(src) as src values(userAgent) as userAgent by user userIdentity.arn 
| where dc_events > 50 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
|`aws_excessive_security_scanning_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_excessive_security_scanning_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
  • eventName
  • src
  • userAgent
  • user
  • userIdentity.arn

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
18.0 30 60 User $user$ has excessive number of api calls $dc_events$ from these IP addresses $src$, violating the threshold of 50, using the following commands $command$.

: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