Detect Multi-Factor Authentication in CrowdStrike LogScale
Adversaries may disable or modify multi-factor authentication (MFA) mechanisms to enable persistent access to compromised accounts. Methods include: excluding users from Azure AD Conditional Access Policies, registering adversary-controlled MFA methods (Scattered Spider), modifying Windows hosts file to redirect MFA server calls to localhost causing fail-open behavior (CISA AA22-074A), using AADInternals Set-AADIntUserMFA to disable MFA, and modifying SLOWPULSE to bypass RADIUS/ACE 2FA. Detection focuses on MFA configuration changes in identity provider audit logs.
MITRE ATT&CK
- Technique
- T1556 Modify Authentication Process
- Sub-technique
- T1556.006 Multi-Factor Authentication
- Canonical reference
- https://attack.mitre.org/techniques/T1556/006/
LogScale Detection Query
// Azure AD MFA modification detection in CrowdStrike LogScale
// Requires Azure AD audit logs ingested via Falcon Data Replicator or Azure Event Hub connector
(#product="azure" #type="auditlog") OR #event_simpleName="AadAuditEvent"
| operationName = /(?i)(Disable StrongAuthentication|User (registered|deleted) security info|Admin (deleted|disabled) (security info|MFA)|Update per-user MFA|Add conditional access policy|Update conditional access policy|Delete conditional access policy)/
| case {
operationName = /(?i)(Disable.*MFA|Admin.*disable.*MFA|Admin.*deleted.*security|Delete.*security.*info)/ | Risk := "HIGH" ;
operationName = /(?i)(User.*deleted.*security.*info|Remove.*authenticat)/ | Risk := "HIGH" ;
operationName = /(?i)(conditional.*access.*policy|Update.*conditional|Add.*conditional)/ | Risk := "MEDIUM" ;
* | Risk := "LOW"
}
| Actor := coalesce(initiatedByUserPrincipalName, userPrincipalName, UserName, "unknown")
| Target := coalesce(targetUserPrincipalName, targetObjectId, ObjectId, "unknown")
| table([_time, Actor, Target, operationName, resultDescription, Risk])
| sort(_time, order=desc)Detects MFA modification and Conditional Access policy changes in Azure AD audit logs ingested into CrowdStrike LogScale via Falcon Data Replicator or an Azure Event Hub connector. Covers both direct MFA configuration changes and Conditional Access policy lifecycle events. To detect endpoint-based MFA bypass via hosts file redirection (CISA AA22-074A), augment with a separate Windows file write detection on C:\Windows\System32\drivers\etc\hosts containing entries that resolve to 127.0.0.1 for known MFA provider FQDNs.
Data Sources
Required Tables
False Positives & Tuning
- Identity governance tooling (e.g., SailPoint IIQ, Saviynt) performing authorised bulk MFA re-enrolment that generates large volumes of security info registration events with service account actors
- Azure AD Connect Health agents triggering StrongAuthentication attribute synchronisation during hybrid identity health checks in environments with on-premises AD FS
- Scheduled Conditional Access policy review automation that programmatically applies approved policy baseline templates across multiple Azure AD tenants managed from a central governance platform
Other platforms for T1556.006
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Disable MFA for a User via Microsoft Graph API
Expected signal: Azure AD Audit Log: OperationName 'User deleted security info' or 'Update user' with StrongAuthenticationRequirement modification. Graph API call logged in Azure AD diagnostic logs. PowerShell ScriptBlock Log Event ID 4104.
- Test 2Add Trusted Location to Conditional Access Policy
Expected signal: Azure AD Audit Log: OperationName 'Add named location' with the new IP range visible in audit details. Azure AD Audit Log: If location is then added as exclusion to a CA policy, OperationName 'Update conditional access policy'.
- Test 3Modify Windows Hosts File to Redirect MFA Server (CISA AA22-074A Pattern)
Expected signal: Sysmon Event ID 11 (File Create/Modify): TargetFilename=C:\Windows\System32\drivers\etc\hosts, initiated by powershell.exe. Windows Defender may alert on hosts file modification. Security Event ID 4663 if file auditing is enabled.
References (6)
- https://attack.mitre.org/techniques/T1556/006/
- https://www.cisa.gov/uscert/ncas/alerts/aa22-074a
- https://www.mandiant.com/media/17826
- https://docs.microsoft.com/en-us/azure/active-directory/governance/conditional-access-exclusion
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1556.006/T1556.006.md
- https://www.microsoft.com/en-us/security/blog/2022/10/25/microsoft-incident-response-tips-for-managing-a-phishing-crisis/
Unlock Pro Content
Get the full detection package for T1556.006 including response playbook, investigation guide, and atomic red team tests.