Multi-Factor Authentication (MFA)
A security principle that strengthens authentication by requiring multiple independent factors, e.g. knowledge, possession, or biometric attributes.
Classification
- ComplexityMedium
- Impact areaOrganizational
- Decision typeArchitectural
- Organizational maturityIntermediate
Technical context
Principles & goals
Use cases & scenarios
Compromises
- SIM swapping for SMS-based factors.
- Loss of hardware tokens without robust emergency processes.
- Misconfigurations that render MFA bypassable.
- Favor phishing-resistant factors (e.g. FIDO2) over SMS.
- Use adaptive MFA to balance usability and security.
- Implement clear emergency and recovery procedures.
I/O & resources
- Existing identity directory (LDAP, AD, IdP)
- List of supported authentication factors
- Risk policies and compliance requirements
- Active MFA policy and configuration sets
- Audit logs with second-factor events
- Reports on adoption and effectiveness
Description
Multi-factor authentication (MFA) is a security approach that strengthens identity verification by requiring two or more independent factors such as knowledge, possession, or inherence. MFA reduces the risk of credential compromise and aids regulatory compliance. Implementation requires integration with identity providers and balancing security, usability, and operational cost.
✔Benefits
- Significant reduction of account takeover via stolen passwords.
- Supports regulatory and compliance requirements.
- Increased traceability and forensic capability for authentication events.
✖Limitations
- Not all factors are equally secure (e.g. SMS vs. hardware tokens).
- Implementation can introduce additional operational overhead.
- User acceptance can suffer with poor UX and lead to workarounds.
Trade-offs
Metrics
- Share of MFA-enabled accounts
Percentage of users who have enabled MFA.
- Number of prevented account takeovers
Detected or prevented takeover attempts after MFA rollout.
- Support tickets for lost factors
Number relative to user base requiring help for lost factor.
Examples & implementations
MFA via TOTP for internal tools
A team introduces TOTP authenticators for internal web apps and connects them to existing SSO.
Hardware tokens for admin accounts
U2F/HSM-backed hardware tokens are mandated for privileged accounts.
Push-based MFA with mobile device
Users confirm login requests via push notifications from a trusted authenticator client.
Implementation steps
Inventory existing authentication flows and IdPs.
Risk-based selection of appropriate authentication factors.
Define mandatory policies and exception rules.
Technical integration with IdP/SSO and testing in pilot groups.
Rollout with user communication, training, and support processes.
⚠️ Technical debt & bottlenecks
Technical debt
- Legacy systems lacking MFA support that require workarounds.
- Temporary exception accounts not cleaned up.
- Incomplete logging integration for factor events.
Known bottlenecks
Misuse examples
- Accepting SMS codes as sole protection for admin accounts.
- Storing backup codes in unencrypted notes.
- Allowing long-term exceptions without review.
Typical traps
- Overestimating the security of SMS or email factors.
- Insufficient procedures for factor loss or rotation.
- Lack of integration into audit and incident processes.
Required skills
Architectural drivers
Constraints
- • Legal constraints regarding biometric data handling
- • Technical limitations of legacy applications
- • Budget constraints for tokens, services, and integration