CHAIN-072 — Group with external owners creates persistence

Summary

Severity: High · Likelihood: Medium · Logic: ALL

Why this chain matters

A Microsoft 365 / Entra group has an external (guest) user listed as owner. Guest owners can edit membership and — depending on group settings — modify role assignments. A partner breach turns into a home tenant persistence mechanism.

Component rules

This chain fires when its trigger conditions are met by the following rules. Click any rule to see its detection logic and compliance mappings.

Rule ID	Role
zt_id_024	Trigger
zt_id_023	Trigger

Attack walkthrough

Step 1 — Compromise the guest owner account on the partner side.

Actor: Partner attacker
MITRE ATT&CK: T1078.004
Enabled by: zt_id_023

Attacker gain: Guest account with ownership.

Step 2 — Add attacker-controlled user object to the group; role inherits.

Actor: Guest owner
MITRE ATT&CK: T1098
Enabled by: zt_id_024

Attacker gain: Persistent privileged membership.

Blast radius

Initial access	Partner tenant compromise.
Max privilege	Home tenant group role.
Data at risk	Home tenant directory objects reachable via the group's role
Services at risk	Entra ID, M365 groups

How the logic works

The chain fires only when every rule above has at least one finding in the current scan. Missing any one rule breaks the chain — so remediating any single step disrupts the attack path.