Detect Multi-Factor Authentication in Elastic Security
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/
Elastic Detection Query
any where event.dataset in ("azure.auditlogs", "o365.audit") and (
(
(event.action like~ "*StrongAuthentication*"
or event.action like~ "*MFA*"
or event.action in~ ("User registered security info", "User deleted security info",
"Admin deleted security info", "Update per-user MFA", "Update user"))
and (
azure.auditlogs.result_description like~ "*StrongAuthenticationRequirement*"
or azure.auditlogs.result_description like~ "*MFA*"
or azure.auditlogs.result_description like~ "*authenticator*"
or azure.auditlogs.result_description like~ "*phone*"
or event.action like~ "*StrongAuthentication*"
or event.action like~ "*MFA*"
)
)
or
(
azure.auditlogs.properties.logged_by_service like~ "*Conditional Access*"
and event.action in~ ("Add conditional access policy", "Update conditional access policy",
"Delete conditional access policy")
)
)Detects MFA disable/modification operations and Conditional Access policy changes in Azure AD audit logs ingested via the Elastic Azure integration or Filebeat azure module. Covers StrongAuthentication changes, security info deletion by admins, per-user MFA updates, and Conditional Access policy lifecycle events.
Data Sources
Required Tables
False Positives & Tuning
- IT or identity administrators legitimately disabling per-user MFA in favour of Conditional Access-based enforcement during an approved policy migration project
- End users registering a replacement MFA method (new phone, new authenticator app) during authorised onboarding or device refresh cycles
- Automated infrastructure-as-code pipelines (Terraform azuread provider, Bicep templates) updating Conditional Access policies during scheduled maintenance change windows
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/
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