T1621 Multi-Factor Authentication Request Generation

credential access — Windows, Linux, macOS, IaaS, SaaS, Office Suite, Identity Provider · attack.mitre.org · JSON

MITRE detection strategy

analytics

Sigma rules tagged attack.t1621

KEV CVEs mapped here

Adversaries may attempt to bypass multi-factor authentication (MFA) mechanisms and gain access to accounts by generating MFA requests sent to users.Adversaries in possession of credentials to Valid Accounts may be unable to complete the login process if they lack access to the 2FA or MFA mechanisms required as an additional credential and security control. To circumvent this, adversaries may abuse the automatic generation of push notifications to MFA services such as Duo Push, Microsoft Authenticator, Okta, or similar services to have the user grant access to their account. If adversaries lack credentials to victim accounts, they may also abuse automatic push notification generation when this option is configured for self-service password reset (SSPR).In some cases, adversaries may continuously repeat login attempts in order to bombard users with MFA push notifications, SMS messages, and phone calls, potentially resulting in the user finally accepting the authentication request in response to “MFA fatigue.”

KEV CVEs mapped to this technique · CTID Mappings Explorer

None. No KEV entry in the public mapping names this technique. Given that 74.7% of KEV has no mapping at all, this says more about the mapping than about the technique.

Detection strategy · ATT&CK Enterprise v19.2

DET0160 Detection Strategy for Multi-Factor Authentication Request Generation (T1621) v1.0
AN0449 Identity Provider
Monitor for excessive or anomalous MFA push notifications or token requests, especially when login attempts originate from unusual IPs or geolocations and do not correspond to legitimate user-initiated sessions.

azure:signinlogs Multiple MFA challenge requests without successful primary login → DC0002 User Account Authentication
NSM:Connections PushNotificationSent → DC0038 Application Log Content

Tunable: TimeWindow GeoIPAllowList

AN0450 IaaS
Detect abnormal MFA activity within cloud service provider logs, such as repeated generation of MFA challenges for the same user session or mismatched MFA device and login origin.

AWS:CloudTrail AssumeRole or ConsoleLogin with repeated MFA failures followed by repeated MFA requests → DC0002 User Account Authentication

Tunable: FailedLoginThreshold

AN0451 Windows
Detect repeated failed login events followed by MFA challenges triggered in rapid succession, especially if originating from service accounts or anomalous IP addresses.

WinEventLog:Security EventCode=4625 → DC0002 User Account Authentication

Tunable: ServiceAccountExclusion

AN0452 Linux
Monitor PAM and syslog entries for unusual frequency of login attempts that trigger MFA prompts, particularly when MFA challenges do not match expected user behavior.

auditd:AUTH pam_unix or pam_google_authenticator invoked repeatedly within short interval → DC0002 User Account Authentication

Tunable: AuthRetryThreshold

AN0453 SaaS
Detect anomalous OAuth or SSO logins that repeatedly generate MFA challenges, particularly where MFA approvals are denied or timed out by the user.

saas:okta MFAChallengeIssued → DC0038 Application Log Content

Tunable: MFAProvider

AN0454 macOS
Detect user account logon attempts that trigger multiple MFA challenges through enterprise identity integrations, especially if MFA push requests are generated without successful interactive login.

macos:unifiedlog authd generating multiple MFA token requests → DC0088 Logon Session Metadata

Tunable: DeviceEnrollmentStatus

Sigma rules · SigmaHQ da9bb07d64, tag `attack.t1621`

Multifactor Authentication Interrupted mediumtest

Author: AlertIQ · 2021-10-10 (modified 2022-12-18) · logsource: product=azure service=signinlogs · 5496ff55-42ec-4369-81cb-00f417029e25

Identifies user login with multifactor authentication failures, which might be an indication an attacker has the password for the account but can't pass the MFA challenge.