Query: explain T1621 Multi-Factor Authentication Request Generation
Matching passage: T1621 Multi-Factor Authentication Request Generation. Tactics: credential access. Description: 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](https://attack.mitre.org/techniques/T1078) 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).(Citation: Obsidian SSPR Abuse 2023) 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.”(Citation: Russian 2FA Push Annoyance - Cimpanu)(Citation: MFA Fatigue Attacks - PortSwigger)(Citation: Suspected Russian Activity Targeting Government and Business Entities Around the Globe)
Near-miss passage: T1649 Steal or Forge Authentication Certificates. Tactics: credential access. Description: Adversaries may steal or forge certificates used for authentication to access remote systems or resources. Digital certificates are often used to sign and encrypt messages and/or files. Certificates are also used as authentication material. For example, Entra ID device certificates and Active Directory Certificate Services (AD CS) certificates bind to an identity and can be used as credentials for domain accounts.(Citation: O365 Blog Azure AD Device IDs)(Citation: Microsoft AD CS Overview) Authentication certificates can be both stolen and forged. For example, AD CS certificates can be stolen from encrypted storage (in the Registry or files)(Citation: APT29 Deep Look at Credential Roaming), misplaced certificate files (i.e. [Unsecured Credentials](https://attack.mitre.org/techniques/T1552)), or directly from the Windows certificate store via various crypto APIs.(Citation: SpecterOps Certified Pre Owned)(Citation: GitHub CertStealer)(Citation: GitHub GhostPack Certificates) With appropriate enrollment rights, users and/or machines within a domain can also request and/or manually renew certificates from enterprise certificate authorities (CA). This enrollment process defines various settings and permissions associated with the certificate. Of note, the certificate’s extended key usage (EKU) values define signing, encryption, and authentication use cases, while the certificate’s subject alternative name (SAN) values define the certificate owner’s alternate names.(Citation: Medium Certified Pre Owned) Abusing certificates for authentication credentials may enable other behaviors such as [Lateral Movement](https://attack.mitre.org/tactics/TA0008). Certificate-related misconfigurations may also enable opportunities for [Privilege Escalation](https://attack.mitre.org/tactics/TA0004), by way of allowing users to impersonate or assume privileged accounts or permissions via the identities (SANs) associated with a certificate. These abuses may also enable [Persistence](https:/