How can organisations decide when passwordless authentication should replace shared secrets and OTP-based login flows?

Passwordless authentication should replace shared secrets and OTP based flows when the organisation needs stronger resistance to phishing, SIM swapping, and credential replay. It is especially relevant for high value users, privileged access, and externally exposed workflows. Teams should prioritise methods that bind authentication to the device and reduce dependence on reusable secrets and interceptable codes.

Why This Matters for Security Teams

passwordless authentication is not just a usability upgrade. For security teams, the decision is about reducing the attack surface created by shared secrets, reusable passwords, and OTP flows that can be phished, replayed, or intercepted. When access sits behind a secret that can be copied, forwarded, or socially engineered out of a user, the control is only as strong as the weakest path into that secret.

This is why NIST control guidance and the NIST SP 800-53 Rev 5 Security and Privacy Controls increasingly favour stronger authenticator assurance and reduced reliance on memorised credentials. The operational problem is broader than account takeover: shared secrets also expand recovery risk, support burden, and cross-system reuse. NHIMG research on Guide to the Secret Sprawl Challenge shows how credential sprawl turns a single compromise into a multi-system event, especially where login flows still depend on OTPs and manually managed resets.

In practice, many security teams only discover how fragile OTP-based access really is after a phishing kit, SIM swap, or help desk bypass has already converted one login into a broader compromise.

How It Works in Practice

The decision usually starts with matching the authentication method to the risk of the workflow. Passwordless should replace shared secrets and OTP-based login flows first where the user is privileged, externally exposed, or likely to be targeted by phishing. For those contexts, current guidance suggests favouring device-bound authenticators, phishing-resistant authenticators, or passkeys that prove possession of a trusted device rather than a reusable secret.

Implementation is strongest when authentication is paired with policy controls that verify device state, session risk, and user context at runtime. The OWASP Non-Human Identity Top 10 is useful here because the same lesson applies to workloads and agents: reduce dependence on static secrets, and prefer credentials that are scoped, short-lived, and harder to replay. For human users, that means moving away from shared passwords and SMS OTP where possible, then aligning recovery flows, MFA enrollment, and step-up authentication so the old path is not still the easiest path.

A practical rollout often follows this sequence:

• Identify the highest-risk user populations, such as admins, contractors, and externally facing operators.
• Map each login flow to the credential type it depends on, including shared passwords, OTP, backup codes, and help-desk resets.
• Prefer passwordless methods that bind the session to a device or security key rather than a recoverable secret.
• Keep fallback paths narrow, logged, and subject to stronger approval than the primary flow.
• Measure whether the new method reduces phishing success, reset volume, and account recovery abuse.

NHIMG’s 52 NHI Breaches Analysis also reinforces a core pattern: once a secret can be reused across tools, one compromise can cascade into many. These controls tend to break down when legacy applications still require password fallback or when recovery processes remain easier to exploit than the primary login.

Common Variations and Edge Cases

Tighter login control often increases rollout friction, user support demand, and application compatibility work, so organisations must balance phishing resistance against operational cost. That tradeoff is especially visible in hybrid estates where some systems support passkeys or device-bound authenticators and others still depend on OTP or shared service accounts.

Best practice is evolving, but current guidance suggests not treating passwordless as an all-or-nothing replacement. High-value access should move first, while lower-risk workflows may retain OTP temporarily if the business cannot yet support broader change. The key exception is any environment where OTP is being used as a primary safeguard against determined attackers. In those cases, OTP often adds convenience without enough resistance to interception or social engineering.

There is also no universal standard for every recovery model yet. Organisations need to review how lost-device handling, account recovery, and step-up verification work, because weak recovery can undo the benefit of strong primary authentication. Where the login flow supports federated identity, passwordless can also be introduced through the identity provider without rewriting every application at once, which lowers migration risk.

For deeper operational context, the NHIMG analysis in Ultimate Guide to NHIs — Static vs Dynamic Secrets is useful because it shows the same design principle in another domain: replace durable secrets with controlled, context-aware access where possible.

Related resources from NHI Mgmt Group

• Should organisations replace MFA with passwordless authentication?
• How can organisations decide when certificate-based authentication is worth the effort?
• When should organisations replace shared infrastructure access with role-based session controls?
• How should organisations implement passwordless authentication in shared-device environments?