CHAIN-103 — Private DNS zone hijack via delegation

Summary

Severity: High · Likelihood: Low · Logic: ALL

Why this chain matters

Private DNS zones are linked to VNets without strict IAM. An attacker with Private DNS Zone Contributor creates a CNAME for an internal service name to attacker-controlled storage, harvesting internal traffic intended for legitimate endpoints.

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_net_022	Trigger
zt_id_003	Trigger

Attack walkthrough

Step 1 — Add CNAME internal-api -> attacker.blob.core.windows.net.

Actor: Attacker with DNS write
MITRE ATT&CK: T1584.002
Enabled by: zt_net_022

Attacker gain: DNS-based MITM in private plane.

Step 2 — Resolves internal-api to attacker storage; sends auth tokens in request headers.

Actor: Victim app
MITRE ATT&CK: T1557
Enabled by: zt_id_003

Attacker gain: Captured bearer tokens.

Blast radius

Initial access	Private DNS write.
Max privilege	Token capture + future replay.
Data at risk	Any internal service bearer tokens
Services at risk	Every VNet-linked DNS consumer

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.