CHAIN-111 — Private Link DNS misconfig forces fallback to public

Summary

Severity: Medium · Likelihood: Medium · Logic: ALL

Why this chain matters

A storage account has Private Link but the private DNS zone is not linked to the consuming VNet. DNS falls back to the public endpoint; traffic now traverses the public internet instead of the private channel. The admin thinks it's private; it isn't.

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_data_002	Trigger

Attack walkthrough

Step 1 — VNet resolves *.blob.core.windows.net to the public IP.

Actor: Misconfig
MITRE ATT&CK: T1584.002
Enabled by: zt_net_022

Attacker gain: Traffic goes over public Internet.

Step 2 — Sniff the assumed-private traffic.

Actor: External adversary
MITRE ATT&CK: T1040
Enabled by: zt_data_002

Attacker gain: Plaintext-on-TLS exfil + MITM potential.

Blast radius

Initial access	Routing-level path exposure.
Max privilege	Internet adversary observability.
Data at risk	Supposedly private storage traffic
Services at risk	Any Private Link consumer with broken DNS

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.