Detection: AWS Defense Evasion Update Cloudtrail

Updated Date: 2024-05-17 ID: 7c921d28-ef48-4f1b-85b3-0af8af7697db Author: Gowthamaraj Rajendran, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects UpdateTrail events in AWS CloudTrail logs. It identifies attempts to modify CloudTrail settings, potentially to evade logging. The detection leverages CloudTrail logs, focusing on UpdateTrail events where the user agent is not the AWS console and the operation is successful. This activity is significant because altering CloudTrail settings can disable or limit logging, hindering visibility into AWS account activities. If confirmed malicious, this could allow attackers to operate undetected, compromising the integrity and security of the AWS environment.

1`cloudtrail` eventName = UpdateTrail eventSource = cloudtrail.amazonaws.com userAgent !=console.amazonaws.com errorCode = success
2| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.name) as cloudtrail_name by src region eventName userAgent user_arn aws_account_id 
3| `security_content_ctime(firstTime)`
4| `security_content_ctime(lastTime)`
5| `aws_defense_evasion_update_cloudtrail_filter`

Data Source

Name Platform Sourcetype Source Supported App
AWS CloudTrail UpdateTrail AWS icon AWS 'aws:cloudtrail' 'aws_cloudtrail' N/A

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_defense_evasion_update_cloudtrail_filter search *
aws_defense_evasion_update_cloudtrail_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1562 Impair Defenses Defense Evasion
T1562.008 Disable or Modify Cloud Logs Defense Evasion
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
Magic Hound
APT29

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

You must install Splunk AWS Add on and enable CloudTrail logs in your AWS Environment.

Known False Positives

While this search has no known false positives, it is possible that an AWS admin has updated cloudtrail logging. Please investigate this activity.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $user_arn$ has updated a cloudtrail logging for account id $aws_account_id$ from IP $src$ 90 100 90
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset aws_cloudtrail aws:cloudtrail
Integration ✅ Passing Dataset aws_cloudtrail aws:cloudtrail

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: GitHub | Version: 2