Detection: AWS High Number Of Failed Authentications From Ip

Updated Date: 2024-09-30 ID: f75b7f1a-b8eb-4975-a214-ff3e0a944757 Author: Bhavin Patel, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects an IP address with 20 or more failed authentication attempts to the AWS Web Console within a 5-minute window. This detection leverages CloudTrail logs, aggregating failed login events by IP address and time span. This activity is significant as it may indicate a brute force attack aimed at gaining unauthorized access or escalating privileges within an AWS environment. If confirmed malicious, this could lead to unauthorized access, data breaches, or further exploitation of AWS resources.

Search

1`cloudtrail` eventName=ConsoleLogin action=failure 
2| bucket span=5m _time 
3| stats dc(_raw) AS failed_attempts values(user_name) as tried_accounts values(user_agent) by _time, src_ip, eventName, eventSource aws_account_id 
4| where failed_attempts > 20 
5|  `aws_high_number_of_failed_authentications_from_ip_filter`

Data Source

Name	Platform	Sourcetype	Source
AWS CloudTrail ConsoleLogin	AWS	`'aws:cloudtrail'`	`'aws_cloudtrail'`

Macros Used

Name	Value
cloudtrail	`sourcetype=aws:cloudtrail`
aws_high_number_of_failed_authentications_from_ip_filter	`search *`

aws_high_number_of_failed_authentications_from_ip_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
T1110	Brute Force	Credential Access
T1110.003	Password Spraying	Credential Access
T1110.004	Credential Stuffing	Credential Access

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT28

APT38

APT39

APT41

Agrius

DarkVishnya

Dragonfly

Ember Bear

FIN5

Fox Kitten

HEXANE

OilRig

Turla

APT28

APT29

APT33

Agrius

Chimera

Ember Bear

HEXANE

Lazarus Group

Leafminer

Silent Librarian

Chimera

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 Add-on for AWS in order to ingest Cloudtrail. We recommend the users to try different combinations of the bucket span time and the tried account threshold to tune this search according to their environment.

Known False Positives

An Ip address with more than 20 failed authentication attempts in the span of 5 minutes may also be triggered by a broken application.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Multiple failed console login attempts (Count: $failed_attempts$) against users from IP Address - $src_ip$	54	60	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: 3