Detection: AWS Successful Console Authentication From Multiple IPs

Updated Date: 2024-09-24 ID: 395e50e1-2b87-4fa3-8632-0dfbdcbcd2cb Author: Bhavin Patel, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects an AWS account successfully authenticating from multiple unique IP addresses within a 5-minute window. It leverages AWS CloudTrail logs, specifically monitoring ConsoleLogin events and counting distinct source IPs. This behavior is significant as it may indicate compromised credentials, potentially from a phishing attack, being used concurrently by an adversary and a legitimate user. If confirmed malicious, this activity could allow unauthorized access to corporate resources, leading to data breaches or further exploitation within the AWS environment.

1`cloudtrail` eventName = ConsoleLogin 
2| bin span=5m _time 
3| stats values(userAgent) as userAgent values(eventName) as eventName values(src_ip) as src_ip dc(src_ip) as distinct_ip_count by _time user_arn 
4| where distinct_ip_count>1 
5| `aws_successful_console_authentication_from_multiple_ips_filter`

Data Source

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

Macros Used

Name Value
cloudtrail sourcetype=aws:cloudtrail
aws_successful_console_authentication_from_multiple_ips_filter search *
aws_successful_console_authentication_from_multiple_ips_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
T1535 Unused/Unsupported Cloud Regions Defense Evasion
KillChainPhase.EXPLOITAITON
KillChainPhase.WEAPONIZATION
NistCategory.DE_AE
Cis18Value.CIS_10

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 True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

You must install Splunk AWS add on and Splunk App for AWS. This search works when AWS CloudTrail events are normalized use the Authentication datamodel.

Known False Positives

A user with successful authentication events from different Ips may also represent the legitimate use of more than one device. Filter as needed and/or customize the threshold to fit your environment.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
User $user_arn$ has successfully logged into the AWS Console from different IP addresses $src_ip$ within 5 mins 72 90 80
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: 4