They create risk because the account is most exposed before MFA enrolment, device trust, and user awareness are established. A temporary passcode can be enough to get a new hire into the system, but if it is delivered through weak channels or has a broad lifespan, it remains a real access secret.
Why temporary onboarding credentials are still a real exposure
Temporary onboarding credentials sit in the gap between account creation and mature access control. Even in a passwordless programme, that gap matters because the first sign-in often happens before device trust, phishing-resistant enrolment, and recovery protections are fully in place. A temporary passcode is still an authenticating secret, so its delivery path, lifespan, and scope all determine how much risk it creates.
Temporary credentials also tend to be used at the moment when support teams are moving quickly, which increases the chance of broad delivery channels, weak verification, or reuse across users. That is why the issue is less about whether the final programme is passwordless and more about whether the onboarding bridge is controlled as carefully as the steady-state sign-in path.
Where the risk comes from in the onboarding flow
The main weakness is that onboarding credentials are often treated as disposable, even though they can be enough to establish initial access. If the credential is sent by email or SMS, forwarded by a help desk, or left valid for too long, it becomes a usable entry point rather than a narrow bootstrap step. The shorter the path from issuance to enrolment, the smaller the exposure window.
There is also a sequencing problem. Passwordless controls are strongest after the user has enrolled a device, established a trusted authenticator, and completed the intended recovery path. Before that point, the account may still depend on weaker fallback methods. That is why passwordless rollout guidance should be read together with Passwordless and Passkeys Guide, which covers the transition from bootstrap access to phishing-resistant sign-in.
Temporary onboarding secrets are also vulnerable because they are frequently shared through the same channels that attackers target for social engineering. A one-time onboarding code is not equivalent to a passwordless authenticator, and if the code can be intercepted, relayed, or reused, the attacker may win the race before the stronger controls are active.
How to keep the bridge narrow without weakening onboarding
The practical objective is to make the temporary credential do one job only: prove enough to start enrolment, then die quickly. The best controls here are short expiry, single use where feasible, narrow scope, and delivery through channels that are already bound to the expected user. If a temporary code can still open broader account functions, it has not been constrained tightly enough.
Onboarding also needs lifecycle discipline, because temporary access becomes risky when it is not revoked after use. That is especially important where onboarding intersects with broader identity processes such as joiner activation, help desk resets, or post-hire provisioning. NHIMG’s Joiner-Mover-Leaver (JML) Guide and Workforce Identity Security Guide both reinforce the same operational point: early account states need stronger handling, not lighter handling.
For teams that want the bridging mechanism described more concretely, Passwordless and Passkeys Guide is the right conceptual anchor because it links onboarding to phishing-resistant sign-in, recovery design, and the transition away from temporary access methods.
Risk and Threat Considerations
Temporary onboarding credentials become attractive when an attacker can intercept the delivery channel, reuse a code before expiry, or pressure support staff into bypassing verification. The real danger is not the temporary credential itself, but the short period in which it can authenticate a fresh account before stronger controls are active.
Failure mechanism: Weak delivery, excessive validity, or inconsistent enrolment checks let a one-time onboarding secret function as a practical access token rather than a limited bootstrap control.
Impact: An attacker who gets the temporary code first may establish account access, enrol a trusted device, or set up persistent recovery options before the intended user completes onboarding.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 addresses the attack and risk surface, while NIST SP 800-63, NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-63 | Digital Identity Guidelines | Covers authenticator assurance and phishing-resistant sign-in during onboarding. |
| Recommendation — Use phishing-resistant enrollment and recovery paths before granting broader account access. | ||
| OWASP Non-Human Identity Top 10 | NHI-02 — Secret Leakage | Temporary onboarding codes are secrets whose exposure creates immediate access risk. |
| NHI-07 — Long-Lived Secrets | Expiry and reuse window are central to onboarding credential risk. | |
| Recommendation — Minimise secret exposure during issuance, delivery, and first use. Set very short lifetimes and revoke onboarding credentials after enrolment. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Temporary credentials need lifecycle controls, expiration, and revocation. |
| IA-2 — Identification and Authentication (Organizational Users) | Onboarding credentials are part of initial user authentication before full enrolment. | |
| Recommendation — Enforce expiry, revocation, and secure distribution for onboarding authenticators. Require strong initial authentication before enabling wider account access. | ||
| OWASP ASVS | V6 — Authentication | Initial sign-in controls and recovery flows directly affect temporary onboarding access. |
| Recommendation — Harden first-login and recovery flows so bootstrap secrets cannot become persistent access. | ||
Practitioner Guidance
What to prioritise: Treat onboarding credentials as a high-risk access path until the user has completed phishing-resistant enrolment and recovery. The control question is not “does the programme use passwords?”, it is “what can this temporary secret unlock before the stronger authenticator is bound to the account?”
What to verify: Confirm that onboarding secrets are single-purpose, short-lived, and invalidated immediately after successful enrolment. Also verify that the help desk cannot extend their usefulness informally, because the exception path is often where the risk becomes material.
Common mistake: Teams often harden the steady-state sign-in flow but leave onboarding as a convenience process. That creates a weak first-contact channel that attackers can target before passwordless protections are fully established.
Practitioner takeaway: Passwordless reduces long-term credential risk, but the onboarding bridge must be designed as if it were a real access secret, because that is exactly what it is until stronger trust is in place.