CHAIN-166 — Service Bus Relay without authentication

Summary

Severity: High · Likelihood: Low · Logic: ALL

Why this chain matters

A WCF Service Bus Relay exposes an on-prem service to the internet without authentication. Anyone who discovers the relay URL reaches the backend service directly — bypassing corporate perimeter controls.

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_int_004	Trigger
zt_wl_002	Trigger

Attack walkthrough

Step 1 — Enumerate *.servicebus.windows.net for relay endpoints.

Actor: Attacker
MITRE ATT&CK: T1595
Enabled by: zt_int_004

Attacker gain: Reachable on-prem service.

Step 2 — Exploit the backend app directly.

Actor: Attacker
MITRE ATT&CK: T1190
Enabled by: zt_wl_002

Attacker gain: Backend compromise.

Blast radius

Initial access	Internet + enumeration.
Max privilege	Backend app RCE.
Data at risk	Backend service data
Services at risk	On-prem app behind the relay

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.