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.

Search

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	`'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

AWS Defense Evasion

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

https://attack.mitre.org/techniques/T1562/008/

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