Detection: Detect AWS Console Login by New User

EXPERIMENTAL DETECTION

This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-05-28 ID: bc91a8cd-35e7-4bb2-6140-e756cc46fd71 Author: Rico Valdez, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects AWS console login events by new users. It leverages AWS CloudTrail events and compares them against a lookup file of previously seen users based on ARN values. This detection is significant because a new user logging into the AWS console could indicate the creation of new accounts or potential unauthorized access. If confirmed malicious, this activity could lead to unauthorized access to AWS resources, data exfiltration, or further exploitation within the cloud environment.

Search

 1
 2| tstats earliest(_time) as firstTime latest(_time) as lastTime from datamodel=Authentication where Authentication.signature=ConsoleLogin by Authentication.user 
 3| `drop_dm_object_name(Authentication)` 
 4| join user type=outer [ 
 5| inputlookup previously_seen_users_console_logins 
 6| stats min(firstTime) as earliestseen by user] 
 7| eval userStatus=if(earliestseen >= relative_time(now(), "-24h@h") OR isnull(earliestseen), "First Time Logging into AWS Console", "Previously Seen User") 
 8| where userStatus="First Time Logging into AWS Console" 
 9| `security_content_ctime(firstTime)` 
10| `security_content_ctime(lastTime)` 
11| `detect_aws_console_login_by_new_user_filter`

Data Source

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

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
detect_aws_console_login_by_new_user_filter	`search *`

detect_aws_console_login_by_new_user_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
T1586	Compromise Accounts	Resource Development
T1586.003	Cloud Accounts	Resource Development
T1552	Unsecured Credentials	Credential Access

KillChainPhase.EXPLOITAITON

KillChainPhase.WEAPONIZATION

NistCategory.DE_AE

Cis18Value.CIS_10

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 Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

You must install and configure the Splunk Add-on for AWS (version 5.1.0 or later) and Enterprise Security 6.2, which contains the required updates to the Authentication data model for cloud use cases. Run the Previously Seen Users in CloudTrail - Initial support search only once to create a baseline of previously seen IAM users within the last 30 days. Run Previously Seen Users in CloudTrail - Update hourly (or more frequently depending on how often you run the detection searches) to refresh the baselines.

Known False Positives

When a legitimate new user logins for the first time, this activity will be detected. Check how old the account is and verify that the user activity is legitimate.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
User $user$ is logging into the AWS console for the first time	30	50	60

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

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	Not Applicable	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: 4