Why do passkeys matter more than traditional second factors for app security?

Why passkeys change the app security model

Passkeys matter more than traditional second factors because they change what the app is defending. A passkey is not just an extra code after a password, it is a phishing-resistant authenticator that is bound to the origin and tied to a device or synced credential model. That removes the easiest replay path, which is often the real weakness in app sign-in.

Traditional second factors still leave the first factor in place, and that means the app remains exposed to password reuse, credential stuffing, phishing, and help-desk or recovery abuse. A passkey reduces the number of places an attacker can intercept, replay, or socially engineer their way into the account. For app teams, that is a material improvement in sign-in assurance, not just a nicer login experience. NHIMG’s Passwordless and Passkeys Guide is the clearest companion for the rollout and recovery side of that change.

In practice, the difference shows up in the attack surface. With SMS, one-time codes, or push prompts, the user is still often being asked to prove possession through a channel attackers can phish, relay, SIM-swap, fatigue, or intercept. Passkeys move the proof into a cryptographic exchange that resists those common failure modes. That makes the authentication step far less dependent on user vigilance and far more dependent on the cryptographic binding the app can actually trust. For the broader workforce and customer sign-in pattern, the Workforce Identity Security Guide covers how phishing-resistant sign-in, federation, and account recovery fit together.

Where traditional second factors still fail

Second factors are only valuable when the whole flow is resistant to interception and social engineering. OTPs can be phished in real time, SMS can be hijacked through telecom abuse, and push-based approvals can be worn down through repeated prompts. Even when the second factor works, the underlying password remains a standing secret that attackers can target first, which means the app still carries more replay and reset risk than many teams realize.

That is why passkeys are not just another MFA option. They reduce dependence on reusable secrets and shift the sign-in design toward origin-bound cryptographic proof. In security terms, that removes a large class of credential replay and adversary-in-the-middle attacks that commonly defeat traditional factors. The practical consequence is that your fallback and recovery paths matter more, because attackers often go after the weakest remaining route rather than the passkey itself. NHIMG’s MFA Guide is useful when comparing older factors against phishing-resistant sign-in patterns.

For app security teams, the key question is not whether MFA exists, but whether the chosen factor can be replayed, relayed, or socially engineered at scale. If the answer is yes, then the control may still be acceptable for low-risk use cases, but it is not in the same class as a passkey for protecting higher-value sessions. External guidance from NIST SP 800-63 Digital Identity Guidelines aligns with that distinction through its focus on phishing-resistant authentication and assurance levels.

What app teams should plan for when moving to passkeys

The security gain is real, but it is not free. Passkey adoption changes enrollment, account recovery, device replacement, cross-device login, and support workflows. If those pieces are weak, users will fall back to older paths, and the weakest fallback becomes the practical control that attackers will target. That is where many migrations underperform: the passkey is strong, but the exception handling is not.

What to verify: make sure your app can enforce passkey-first sign-in for the right risk tier, while still keeping recovery and support flows phishing-resistant. Check whether account recovery, help-desk reset, and step-up flows are stronger than the legacy factor they replace. If users can bypass passkeys through an easier fallback, the security benefit shrinks quickly.

Common mistake: teams sometimes add passkeys without removing or hardening SMS, OTP, or weak reset paths. That leaves the application with a strong front door and a weak side entrance. The better pattern is to treat passkeys as part of the entire authentication journey, including enrollment, recovery, and session protection. For a deeper failure-mode view, the Twilio 0ktapus breach 2022 is a useful reminder of how easily traditional second factors can be targeted at scale.

Practitioner takeaway: Passkeys matter most when the app team is willing to redesign recovery and fallback paths, because the strongest authenticator on the front end is only as good as the weakest path left behind.

Related resources from NHI Mgmt Group

• When should organisations prioritise hardware security keys over SMS or app-based second factors?
• How should enterprises evaluate Security Keys against OTP and app-based second factors?
• How should security teams authenticate AI agents in enterprise environments?
• How should security teams implement Client ID Metadata Documents?