Security checks / Check reference / Logging & threat detection
Log Cross Tenant Signin
Medium Severity Microsoft 365 security check in the Logging & threat detection domain.
Sign-in originated from an external tenant (cross-tenant) External tenant sign-ins may indicate B2B guest access or compromised credentials being used from an attacker-controlled tenant Siemserva runs this check automatically across your tenant and maps every finding to the compliance frameworks below.
Check summary
What this check verifies
Sign-in originated from an external tenant (cross-tenant)
Why it matters
External tenant sign-ins may indicate B2B guest access or compromised credentials being used from an attacker-controlled tenant
How to fix it
Review cross-tenant access settings; restrict external identities to approved tenants; monitor for unexpected home tenant IDs
Siemserva flags every tenant where this check fails and, with Senserva Trustworthy AI remediation, can propose a validated fix you approve before it applies.
Ask your own AI about this check
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Compliance framework mappings
Findings from this check serve as evidence for:
References
Related Logging & threat detection checks
Common questions
What does the Log Cross Tenant Signin check verify?
Sign-in originated from an external tenant (cross-tenant) It is a Medium Severity check in the Logging & threat detection domain, one of the 650+ checks Siemserva runs across Microsoft 365, Intune, Defender, and Entra ID.
How do I fix a Log Cross Tenant Signin finding?
Review cross-tenant access settings; restrict external identities to approved tenants; monitor for unexpected home tenant IDs Siemserva ranks the finding by Severity and, with Senserva Trustworthy AI, can propose a validated, approve-before-apply configuration fix.
Which compliance frameworks does this check evidence?
Findings from this check map to SCuBA, MCSB, NIST, SOC2, CIS, HIPAA, including SCuBA policy MS.AAD.4.1v1, and MCSB controls IM-6, LT-3. That mapping is what turns a scan finding into audit evidence.
Can I ask my own AI about this check?
Yes. This page includes a free copy-paste AI prompt carrying the check's facts: what it verifies, the risk, the remediation, and the framework mappings. Paste it into Claude, ChatGPT, or Copilot; cite-worthy detail without giving an AI access to your tenant.
All 672 checks with severities and mappings: the Microsoft 365 security checks catalog.