Security teams should review Entra ID non-interactive sign-in logs, not just interactive login events, because older protocols and service-to-service flows can hide attack activity. Look for spikes in repeated failed attempts, unusual user agents such as fasthttp, and login patterns tied to legacy email or device paths. The key is to treat logging coverage as part of the control, not an afterthought.
Why non-interactive sign-in paths matter for detection
Non-interactive sign-ins are often the place where password-spraying shows up first in Microsoft 365, because attackers prefer paths that do not trigger the same user-visible prompts or MFA patterns as interactive logins. Security teams should treat these events as primary telemetry, especially for legacy protocols and service-to-service access that can blend into normal background activity.
The operational mistake is to build detection only around interactive authentication. That leaves a blind spot where repeated failures can accumulate across older email clients, device flows, or other non-browser paths without ever looking like a classic login attack.
Good coverage means correlating sign-in failures with account population, protocol type, and source behavior rather than relying on a single failed-login threshold. For Microsoft 365 environments, the question is not whether the activity is interactive, but whether the pattern shows repeated credential guessing across paths that still accept authentication.
Security teams can deepen their analysis with the Ultimate Guide to Non-Human Identities, which explains why visibility gaps, credential sprawl, and legacy access paths make authentication monitoring harder. The broader lifecycle view in the NHI Lifecycle Management Guide is also useful when sign-in anomalies involve long-lived accounts or access paths that were never tightly governed.
What to look for in the logs
Detection should begin in Entra ID non-interactive sign-in logs, then expand to patterns that are easy to miss in aggregate. Repeated failures against the same tenant, user, or protocol, especially when spread over time instead of clustered into a single burst, are a common spraying signature.
Useful indicators include unusual user agents, atypical source geographies or IP ranges, and authentication attempts tied to older mail or device protocols that remain enabled for compatibility. Strings such as fasthttp are not a verdict on their own, but they can help separate routine client behavior from automation at scale.
Teams should also compare non-interactive failures with successful authentications from the same account family. A spray campaign often produces a noisy set of denied attempts followed by a small number of wins, and that change in pattern is more important than any single failed event.
For practitioners who want a broader control lens, the same problem is consistent with NIST Cybersecurity Framework 2.0 under detect and respond, and with the MITRE ATT&CK Enterprise Matrix for credential access and adversary behavior mapping. In Microsoft-specific environments, the Microsoft Midnight Blizzard breach is a reminder that legacy or weakly governed authentication paths can be a material attack surface.
How to make the detection operationally useful
The best detections do more than count failures. They group attempts by account, protocol, source, and time window, then alert when the same credentials are probed across multiple non-interactive paths or across many accounts from a common source.
What to verify: Confirm that your logging includes non-interactive sign-ins, not just interactive events, and that you can break out legacy protocol activity separately. If the telemetry cannot distinguish these paths, the control is incomplete even if the dashboard looks healthy.
Decision rule: If failures are concentrated in non-interactive access and the user agents or protocols look automated, prioritize investigation and containment before tuning thresholds. If the pattern is tied to a known legacy client or integration, treat it as an access-governance issue, not just a detection event.
Where teams already use identity governance or privileged access controls, the relevant discipline is to reduce the number of paths that can authenticate silently in the first place. The Top 10 NHI Issues and the 2024 ESG Report: Managing Non-Human Identities both reinforce the same practitioner lesson: visibility is only useful if it is paired with ownership, review, and timely remediation of risky access paths.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK and OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST CSF 2.0 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | DE.AE — Anomalies and Events are Detected | Non-interactive spray detection relies on spotting repeated failed auth anomalies. |
| DE.CM — Security Continuous Monitoring | The answer depends on continuous review of sign-in telemetry beyond interactive events. | |
| Recommendation — Correlate failed sign-ins across protocols and alert on abnormal authentication patterns. Monitor non-interactive sign-in logs continuously and tune detections for legacy auth paths. | ||
| MITRE ATT&CK | T1110.003 — Password Spraying | The question is specifically about detecting password spraying activity. |
| T1078 — Valid Accounts | Spray campaigns often seek account access using guessed credentials on real accounts. | |
| Recommendation — Map repeated failed sign-ins to password-spraying tactics and hunt for spread across many accounts. Investigate successful non-interactive logons after spray-like failure patterns for valid-account abuse. | ||
| CIS Controls v8 | 8 — Audit Log Management | Detection depends on reviewing the right authentication logs, including non-interactive events. |
| 6 — Access Control Management | Reducing legacy and silent authentication paths improves resistance to spraying. | |
| Recommendation — Ensure non-interactive sign-in logs are collected, retained, and reviewed for spray indicators. Restrict legacy authentication paths and remove unnecessary non-interactive access routes. | ||
| OWASP Non-Human Identity Top 10 | NHI-03 — Credential Rotation and Expiry | Long-lived access paths and credentials increase exposure when spraying succeeds. |
| Recommendation — Rotate and retire long-lived credentials and legacy access paths that amplify spray risk. | ||
Practitioner Guidance
What to prioritize: Build detection around telemetry completeness first. If non-interactive sign-ins are not routinely reviewed, you are not detecting password spraying so much as detecting the subset that happens to surface in interactive logs.
What to measure: Track the volume of failed non-interactive attempts per account, per protocol, and per source pattern, then watch for sudden concentration or broad low-rate spraying across many accounts. That combination is usually more actionable than a simple failure count.
Common mistake: Treating old protocols, service paths, and device-style access as background noise. In practice, these are often the exact routes that let spraying blend into normal authentication churn.
Practitioner takeaway: A strong control is not just a good detection rule, it is full visibility into every authentication path an attacker can abuse, with non-interactive sign-ins treated as first-class security telemetry.
Related resources from NHI Mgmt Group
- How should security teams harden Entra sign-in controls against password spraying without relying on lockout alone?
- How should security teams detect low-and-slow password spraying before attackers reach privileged accounts?
- How should security teams detect password spraying in Active Directory?
- How should security teams defend against password spraying in hybrid identity environments?
