|AuthN Type Number||Authentication Factor||Resistance to Threat|
|Theft via Dynamic MITM Phishing||Guessing / Offline Cracking||MFA Device|
|User Workstation Compromise|
|2||Phone call - See Voice Requirements 1||Low||Low||High||Low||High|
|3||Phone call (VoIP) - See Additional|
VoIP Restrictions 2
|5||SMS (VoIP) See VoIP restrictions 2||Low||Low||Medium||Low||High|
|6||HOTP cell phone software 1,3||Medium||Low||High||Medium||High|
|7||TOTP cell phone software 1,3||Medium||Low||High||Medium||High|
|10||HOTP written (back up codes)||Low||Low||High||High||Low|
|12||FIDO U2F token with password||High||High||High||High||High|
|13||PKI device certificate with|
|14||PKI token certificate wth with token|
- Voice Restrictions: Institutions deploying a phone call based solution for one of their authentication factors must incorporate multi-factor authentication concepts into their security awareness training. Specifically, a prohibition on configuring voicemail greetings to respond to MFA prompts must be in-place and discussed in training. Training should also include the prohibition against using Enterprise passwords on personal devices.
- Additional VoIP Restrictions: The use of VoIP systems (or traditional PBX solutions) that use the Enterprise password for call control or call redirection may not be used. The creators of this document note that accessibility needs can often be addressed using a hardware token instead of a voice-based solution.
- Campus deployers should pay carful careful attention to cell phone security. Some data sources report that the majority of android devices of Android devices are not updated and are thus highly vulnerable. Some vendors have the ability to restrict MFA use to fully patched cell phones. This table assumes that cell phones used for MFA are receiving software updates.