↳ GitHub sourceAnalytics ruleMedium

MFA Rejected by User

Description

'Identifies occurances where a user has rejected an MFA prompt. This could be an indicator that a threat actor has compromised the username and password of this user account and is using it to try and log into the account. Ref : https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins This query has also been updated to include UEBA logs IdentityInfo and BehaviorAnalytics for contextual information around the results. Please note, MFA Failed logons from known IP ranges can be benign depending on the conditional access policies. In case of noisy behavior, consider tuning the source IP ranges or location filter after careful consideration'
Rule type
Scheduled
Version
2.0.4
Declared status
Available
Query frequency
1h
Query period
1h
Trigger
gt 0

Declared MITRE coverage

Declared sources

Metadata from the source file. No dependencies inferred from KQL.

Connectors

Data types

KQL query

Original query, unchanged.

let riskScoreCutoff = 3; //Adjust this score threshold based on volume of results. Activities identified as the most abnormal receive the highest scores (on a scale of 0-10)
SigninLogs
| where ResultType == 500121
| extend additionalDetails_ = tostring(Status.additionalDetails)
| extend UserPrincipalName = tolower(UserPrincipalName)
| where additionalDetails_ =~ "MFA denied; user declined the authentication" or additionalDetails_ has "fraud"
| summarize StartTime = min(TimeGenerated), EndTIme = max(TimeGenerated) by UserPrincipalName, UserId, AADTenantId, FailedIPAddress = IPAddress
| extend Name = tostring(split(UserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(UserPrincipalName,'@',1)[0])
| join kind=leftouter (
    IdentityInfo
    | summarize LatestReportTime = arg_max(TimeGenerated, *) by AccountUPN
    | project AccountUPN, Tags, JobTitle, GroupMembership, AssignedRoles, UserType, IsAccountEnabled
    | summarize
        Tags = make_set(Tags, 1000),
        GroupMembership = make_set(GroupMembership, 1000),
        AssignedRoles = make_set(AssignedRoles, 1000),
        UserType = make_set(UserType, 1000),
        UserAccountControl = make_set(UserType, 1000)
    by AccountUPN
    | extend UserPrincipalName=tolower(AccountUPN)
) on UserPrincipalName
//Below it will be joined with BehaviorAnalytics table to the Failed IP Addresses
| join kind=leftouter (
    BehaviorAnalytics
    | where ActivityType in ("FailedLogOn", "LogOn")
    | where isnotempty(SourceIPAddress)
    | project UsersInsights, DevicesInsights, ActivityInsights, InvestigationPriority, SourceIPAddress, UserName
    | project-rename FailedIPAddress = SourceIPAddress, Name = UserName
    | summarize
      MaxInvestigationScore = max(InvestigationPriority)  // Only retrieve maximum Investigation Property score for both FailedIP and User
    by FailedIPAddress, Name)
on FailedIPAddress, Name  // Joining on both IP and User so as to only return context associated with same user
| extend UEBARiskScore = MaxInvestigationScore
| project-away *1 // removing duplicate columns post outer join from output
| where  UEBARiskScore > riskScoreCutoff
| sort by UEBARiskScore desc 

Declared entities

AccountIP

Related content

Links established from declared identifiers and solution manifests.

Source provenance

GitHub

Displayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.

Source identifier
d99cf5c3-d660-436c-895b-8a8f8448da23
Additional source files 3Solutions/Microsoft Entra ID/Analytic Rules/MFARejectedbyUser.yamlsource ↗Detections/SigninLogs/MFARejectedbyUser.yamlmigration-note ↗Solutions/Microsoft Entra ID/Data/Solution_AAD.jsonsolution-membership ↗
GSTEP / CATALOG TRACKING

Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC

GSTEP sync dates, separate from the source content’s publication dates.