Focus on privileged access first. The highest-value accounts are where phishing-resistant methods deliver the greatest risk reduction, while low-risk populations can be transitioned later without leaving the organisation’s most sensitive systems exposed. Sequencing by blast radius is usually more defensible than a broad, equal-speed migration.
Why sequencing should follow blast radius, not equal speed
The practical decision is less about MFA technology and more about where the failed authentication path would do the most damage. Privileged access, administrative consoles, remote support, and break-glass paths can turn a single phished factor into broad compromise, while ordinary user populations usually offer smaller blast radius. A phased migration is therefore usually safer when it starts with the accounts that can change, delete, or exfiltrate the most.
That is why high-value access paths deserve first attention, especially where legacy SMS or OTP is still accepted on administrator or support workflows. The key question is not “which method is oldest?” but “which account category would let an attacker move fastest if the factor were bypassed or stolen?”
For the privileged-access side of the argument, the Privileged Access Management Guide shows why standing privilege, session control, and vaulting are part of the same risk-reduction problem, not separate workstreams. If a factor protects an account that can reach crown-jewel systems, it is already in the highest-priority queue.
Where SMS and OTP still matter, and where they should wait
SMS and OTP are not equally dangerous in every context, but they are weaker in any path where phishing, relay, SIM swap, token theft, or MFA fatigue can convert one prompt into account takeover. That makes them poor choices for administrator, support, and remote-access scenarios, even if they remain tolerable as a short-term transitional method for low-risk users.
Lower-risk populations can usually be migrated later because their compromise does not normally create immediate enterprise-wide impact. That sequencing is especially defensible when the organisation has limited rollout bandwidth and must prioritise controls that reduce the most harmful failure modes first.
The MFA Guide is useful here because it distinguishes between methods that are merely multi-factor and methods that are actually phishing-resistant. The operational lesson is to reserve the strongest methods for the accounts that would be hardest to recover after compromise.
What a defensible migration plan looks like in practice
A defensible sequence usually starts with privileged users, remote administration, help desk reset paths, and any account that can approve, elevate, or impersonate others. After that, move through service-adjacent and high-trust workflows, then the broader workforce, and finally the remaining low-risk populations. That order reduces the chance that a weak factor remains on the most sensitive paths while the organisation is still “in migration.”
It is also important to treat administrative recovery as part of the rollout. If password reset, account recovery, or emergency access still depends on weak authentication, the new control can be undermined by the fallback path rather than the primary sign-in flow.
For a concrete prioritisation reference, the Workforce Identity Security Guide and the Break-Glass and Emergency Access Account Guide both reinforce the same point: recovery and exception paths must be designed with at least as much care as the normal login path, because attackers often aim for the exception.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 sets the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Covers lifecycle control of authenticators used in MFA replacement. |
| IA-2 — Identification and Authentication (Organizational Users) | Applies to workforce sign-in controls and stronger authentication for users. | |
| IA-9 — Identification and Authentication (Non-Organizational Users) | Relevant where external support or third-party accounts access privileged systems. | |
| Recommendation — Rotate and retire weaker authenticators before broadening rollout to low-risk users. Require stronger sign-in methods for workforce accounts with access to sensitive systems. Enforce stronger authentication on external accounts that can reach privileged environments. | ||
| ISO/IEC 27001:2022 | A.5.15 — Access control | Supports phased access-control strengthening for high-value accounts. |
| A.8.5 — Secure authentication | Directly addresses stronger authentication methods for sensitive access paths. | |
| Recommendation — Prioritise tighter access control on privileged paths before lower-risk user groups. Replace weaker MFA first where secure authentication reduces the largest exposure. | ||
Practitioner Guidance
What to prioritise: migrate privileged administrators, remote support, and break-glass paths first, then enforce a stronger method for any account that can alter identity, access, or production systems. If a factor protects an account with broad reach, it is not a “standard user” problem.
Decision rule: if the account can administer, reset, approve, or pivot into other systems, treat SMS or OTP as temporary at best and plan the move to phishing-resistant methods ahead of the general workforce rollout.
What to verify: check whether any privileged path still accepts weaker MFA through legacy portals, help desk exceptions, or emergency procedures. The common mistake is assuming the main login flow is fixed while recovery, reset, or vendor access still bypasses the new standard.
Practitioner takeaway: sequence MFA replacement by blast radius, not by administrative convenience, because the first accounts you harden are the ones most likely to decide whether a phishing attempt becomes a contained login event or a major compromise.