Detection: High Number of Login Failures from a single source

Updated Date: 2024-09-30 ID: 7f398cfb-918d-41f4-8db8-2e2474e02222 Author: Bhavin Patel, Mauricio Velazco, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects multiple failed login attempts in Office365 Azure Active Directory from a single source IP address. It leverages Office365 management activity logs, specifically AzureActiveDirectoryStsLogon records, aggregating these logs in 5-minute intervals to count failed login attempts. This activity is significant as it may indicate brute-force attacks or password spraying, which are critical to monitor. If confirmed malicious, an attacker could gain unauthorized access to Office365 accounts, leading to potential data breaches, lateral movement within the organization, or further malicious activities using the compromised account.

1`o365_management_activity` Workload=AzureActiveDirectory Operation=UserLoginFailed record_type=AzureActiveDirectoryStsLogon 
2| bucket span=5m _time 
3| stats dc(_raw) AS failed_attempts values(user) as user values(LogonError) as LogonError values(signature) as signature values(UserAgent) as UserAgent by _time, src_ip 
4| where failed_attempts > 10 
5| `high_number_of_login_failures_from_a_single_source_filter`

Data Source

Name Platform Sourcetype Source
O365 UserLoginFailed N/A 'o365:management:activity' 'o365'

Macros Used

Name Value
o365_management_activity sourcetype=o365:management:activity
high_number_of_login_failures_from_a_single_source_filter search *
high_number_of_login_failures_from_a_single_source_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
T1110.001 Password Guessing Credential Access
T1110 Brute Force Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
APT28
APT29
APT28
APT38
APT39
APT41
Agrius
DarkVishnya
Dragonfly
Ember Bear
FIN5
Fox Kitten
HEXANE
OilRig
Turla

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 the Splunk Microsoft Office 365 Add-on and ingest Office 365 management activity events. Adjust the threshold value to suit the specific environment, as environments with naturally higher login failures might generate false positives at a lower threshold.

Known False Positives

An Ip address with more than 10 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
Ip address $src_ip$ failed to authenticate more than 10 times in a 5 minute 25 50 50
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 o365 o365:management:activity
Integration ✅ Passing Dataset o365 o365:management:activity

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