Biometric verification closes the RBA assurance gap in high-risk login

At a glance

What this is: This is an iProov analysis of why risk-based authentication can still fail at the point that matters most, and why biometric verification is positioned as the missing assurance layer.

Why it matters: It matters because IAM teams cannot treat step-up authentication as identity verification in high-risk moments, whether the subject is a human user, an NHI-adjacent workflow, or a broader zero-trust access decision.

👉 Read iProov's analysis of how biometric verification closes the RBA assurance gap

Context

Risk-based authentication tries to balance security and user experience by stepping up checks when login context looks unusual, such as a new location or device. The weakness is that many step-up flows still rely on knowledge or possession factors that do not prove the person at the keyboard is the legitimate subject of the account, which leaves high-risk access decisions exposed.

That gap matters most in zero trust programmes, where every access attempt is supposed to be verified continuously and contextually. When attackers can phish OTPs, spoof devices, or coerce help desks into approving access, the programme is not failing to authenticate more often. It is failing to verify identity at the moment of highest risk.

Key questions

Q: How should security teams reduce MFA bypass risk in high-risk login flows?

A: Use MFA as one layer in a broader assurance model, not as the final proof of identity. For sensitive actions, add liveness-based biometric verification or another strong identity proofing method, then reserve OTPs and push approvals for lower-risk cases where the blast radius is smaller.

Q: When does step-up authentication stop being enough?

A: It stops being enough when the attacker can phish, intercept, coerce, or replay the step-up factor faster than the programme can detect abuse. That is common in account recovery, privileged access, and support-mediated resets, where the control must prove the person rather than the device.

Q: What do teams get wrong about risk-based authentication?

A: They often assume that a successful challenge means the right user is present. In reality, risk-based authentication only says the context looked unusual enough to trigger a check. If the check relies on a weak factor, the system can still grant access to an impostor.

Q: How do zero trust programmes handle identity proof at the point of access?

A: They should separate contextual detection from identity proof. Risk scoring decides when to challenge, but the access decision should rely on a stronger mechanism at high risk, such as liveness verification or another resistant proofing method that cannot be easily shared or intercepted.

Technical breakdown

Why OTP and push-based step-up still fail

One-time passcodes and push approvals are step-up mechanisms, not identity proofs. They confirm access to a channel or device, but not whether the claimant is the real account holder. Attackers exploit this by phishing codes, forcing approval fatigue, SIM-swapping, or hijacking sessions after the first check has succeeded. In practice, the control can detect an unusual context but still hand out access to an impostor if the second factor is easy to coerce or intercept.

Practical implication: treat OTP and push as weak assurance in high-risk workflows, not as a final trust decision.

How biometric liveness changes the assurance model

Biometric verification adds inherence to the authentication equation. Liveness detection matters because image matching alone can be fooled by photos, recordings, or synthetic media, while liveness tests whether a real human is present at the point of verification. In an RBA flow, that shifts the control from factor possession to person verification. The architectural difference is subtle but decisive: the system is no longer asking whether the user has a token, but whether the claimant is physically and temporally present.

Practical implication: place liveness-based verification at the highest-risk checkpoints, especially account recovery and privileged actions.

Zero trust depends on higher-assurance identity signals

Zero trust assumes no implicit trust and continuous verification, but it does not specify a single mechanism for assurance. RBA uses context to decide when to challenge, yet the challenge itself still needs a strong proof of identity. That is why high-risk access paths need stronger signals than device reputation or geography. Once attackers can mimic those signals with AI-assisted phishing, voice cloning, or session emulation, the assurance layer becomes the real control boundary.

Practical implication: pair contextual risk scoring with an identity proofing method that is resistant to phishing and impersonation.

Threat narrative

Attacker objective: The attacker aims to turn a momentary authentication success into durable account control without having to prove legitimate identity.

1. Entry begins with credential theft or social engineering, where the attacker obtains a username, password, or a route into the approval process.
2. Escalation follows when the attacker intercepts OTPs, pushes users into approving MFA prompts, or impersonates the legitimate user to a help desk.
3. Impact occurs when the attacker gains trusted access to the account, then uses that foothold for privileged actions, data access, or lateral movement.

Breaches seen in the wild

• DeepSeek breach — DeepSeek breach exposed 1M+ log lines and sensitive secret keys.
• Schneider Electric credentials breach — exposed credentials gave attackers access to Schneider Electric Jira, exfiltrating 40GB.

Read our 52 NHI Breaches Analysis report for a comprehensive view of breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

Passcode challenge is not identity assurance: RBA often assumes that a successful step-up event means the right person is present. That assumption fails when attackers can intercept OTPs, coerce approvals, or replay the same login from a different location within minutes. The implication is that many programmes are measuring friction, not trust, and that distinction matters most in privileged and recovery flows.

Identity verification must sit above factor verification: A login factor can confirm possession or channel access, but it cannot by itself establish who is behind the screen. When organisations treat MFA as the end of the assurance chain, they leave a gap that AI-assisted phishing and impersonation can exploit at scale. Practitioners should recognise that factor strength and identity certainty are not the same control objective.

Biometric liveness is an assurance control, not a convenience feature: The real value of biometrics in high-risk access is not reduced clicks, it is stronger proof that the claimant is a live human at the moment of verification. That is especially relevant when threat actors can clone voices, emulate devices, and socially engineer support channels. The practitioner takeaway is to anchor biometric use in the highest-value decisions, not in every login.

High-risk access now needs a stronger assurance boundary than traditional MFA provides: The combination of distributed workforces, diverse devices, and AI-enabled impersonation means the old trust cues are degrading faster than many access models can adapt. Runtime assurance gap: This is the named failure mode the article exposes, where contextual risk detection exists but the verification step still fails to establish real identity under attack. Security teams should treat that as a governance problem, not just an authentication tuning issue.

Zero trust programmes must distinguish between detection and proof: Risk signals can tell you that something looks unusual, but they do not prove who the actor is. When attackers have learned to behave like the expected user well enough to pass a challenge, the control has become a screen for suspicious activity rather than an identity test. Practitioners need to understand that challenge frequency alone does not close the assurance gap.

From our research:

• 72% of organisations have experienced or suspect they have experienced a breach of non-human identities, according to The 2024 ESG Report: Managing Non-Human Identities.
• Two-thirds of enterprises have endured a successful cyberattack resulting from compromised non-human identities, with a quarter encountering multiple attacks.
• That pattern points to a broader identity governance problem, which is why practitioners should also review Top 10 NHI Issues for the control failures that allow identity abuse to persist.

What this signals

Runtime assurance gap: Risk-based authentication programmes are increasingly being judged by whether they can prove who is behind the screen, not just whether they can trigger a challenge. Once attackers can imitate location, device context, and voice with enough fidelity, the decisive control shifts from detection to identity proofing, and high-risk access policies need to reflect that change.

The governance signal here is clear: step-up authentication is becoming a weak boundary unless it is paired with a proof method that resists phishing and coercion. In environments where service accounts, human users, and emerging AI-mediated workflows all depend on trustworthy access decisions, organisations should align authentication policy with the strength of the identity signal, not the convenience of the factor.

For practitioners, the next maturity step is to decide where assurance must be strongest and where friction can still be tolerated. That means using NIST Cybersecurity Framework 2.0 to frame the control objective, then tying high-risk access paths to identity proofing methods that can withstand AI-enabled impersonation.

For practitioners

• Prioritise high-risk interactions for stronger verification Use biometric liveness or equivalent identity proofing for account recovery, privileged access, and new device authorisation. Those are the points where a stolen factor has the highest chance of turning into durable account control.
• Reclassify OTP and push as weak assurance Update risk models so one-time passcodes and push approvals are treated as challenge mechanisms, not final proof of identity, especially where fraud, help desk abuse, or impersonation is plausible.
• Hard-check support workflows that can override authentication Review help desk and telecom procedures that can reset access, transfer numbers, or approve new devices. If a human can be persuaded to act as the second factor, the control boundary is already compromised.
• Map zero trust decisions to proof strength Separate the signal that triggers step-up from the method that proves identity. In practice, your access policy should distinguish between contextual risk scoring and the identity proof required before a session is trusted.

Key takeaways

• Traditional MFA can confirm a factor, but it does not always confirm the person behind the access attempt.
• AI-assisted phishing, impersonation, and approval abuse turn risk-based authentication into a weak trust signal when the step-up method is easy to coerce.
• Organizations should reserve stronger biometric or liveness-based proofing for the access paths where a stolen factor would create the most damage.

Key terms

• Risk-Based Authentication: An authentication approach that adjusts the challenge level based on context such as device, location, or behaviour. It is designed to reduce friction for normal activity while stepping up verification when something looks unusual, but it still depends on the strength of the step-up method chosen.
• Biometric Liveness Detection: A control that checks whether a biometric sample comes from a real, present person rather than a photo, replay, or synthetic image. It is important because simple face matching can be fooled, while liveness testing tries to prove the claimant is physically and temporally present at verification time.
• Identity Proofing: The process of establishing that a claimant is the person they say they are before granting access or trust. In modern IAM, proofing must be stronger than a password or push approval if the access path carries high risk, because factors alone do not always establish real identity.
• Zero Trust: A security model that assumes no implicit trust and requires continuous verification before access is granted. For identity programmes, the practical test is whether the organisation can distinguish suspicious context from strong proof of the actor's identity at the point of decision.

Deepen your knowledge

NHI governance, agentic AI identity, and machine identity security are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or programme maturity, it is worth exploring.

This post draws on content published by iProov: Biometric verification closes the RBA assurance gap in high-risk login. Read the original.