Detection: O365 Excessive SSO logon errors

Updated Date: 2026-05-13 ID: 8158ccc4-6038-11eb-ae93-0242ac130002 Author: Rod Soto, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects accounts experiencing a high number of Single Sign-On (SSO) logon errors. It leverages data from the o365_management_activity dataset, focusing on failed user login attempts with SSO errors. This activity is significant as it may indicate brute-force attempts or the hijacking/reuse of SSO tokens. If confirmed malicious, attackers could potentially gain unauthorized access to user accounts, leading to data breaches, privilege escalation, or further lateral movement within the organization.

Search

 1`o365_management_activity` Workload=AzureActiveDirectory LogonError=*Sso* Operation=UserLoginFailed
 2  
 3| stats count min(_time) as firstTime max(_time) as lastTime values(user) as user
 4    BY src vendor_account vendor_product
 5       dest signature user_agent
 6  
 7| where count >= 5
 8  
 9| `security_content_ctime(firstTime)`
10  
11| `security_content_ctime(lastTime)`
12  
13| `o365_excessive_sso_logon_errors_filter`

Data Source

Name	Platform	Sourcetype	Source
O365 UserLoginFailed	Other	`'o365:management:activity'`	`'o365'`

Macros Used

Name	Value
o365_management_activity	`sourcetype=o365:management:activity`
o365_excessive_sso_logon_errors_filter	`search *`

o365_excessive_sso_logon_errors_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
T1556	Modify Authentication Process	Credential Access

Exploitation

Installation

DE.AE

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 Finding (Notable)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

Implementation

You must install splunk Microsoft Office 365 add-on. This search works with o365:management:activity

Known False Positives

Logon errors may not be malicious in nature however it may indicate attempts to reuse a token or password obtained via credential access attack.

Associated Analytic Story

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
Excessive number of SSO logon errors from $src$ using UserAgent $user_agent$.	user	user	20

Threat Objects

Field	Type
src	ip_address

References

https://stealthbits.com/blog/bypassing-mfa-with-pass-the-cookie/

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: 12