CHAIN-195 — GitHub Actions OIDC federation over-scoped

Summary

Severity: High · Likelihood: Medium · Logic: ALL

Why this chain matters

A federated credential trusts any GitHub workflow in any repository under an organisation — the subject claim is too broad. Any repo in the org can assume the identity. A compromised developer's fork becomes cloud-credentialed code execution.

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_011	Trigger
zt_id_008	Trigger

Attack walkthrough

Step 1 — Push malicious workflow to a fork in the org.

Actor: Attacker
MITRE ATT&CK: T1195.002
Enabled by: zt_id_011

Attacker gain: Workflow assumes federated identity.

Step 2 — Use identity's Azure RBAC to exfiltrate.

Actor: Attacker
MITRE ATT&CK: T1078
Enabled by: zt_id_008

Attacker gain: Cloud compromise from fork.

Blast radius

Initial access	Any fork in the org.
Max privilege	Federated identity's RBAC.
Data at risk	Azure resources under that identity
Services at risk	Azure RBAC via OIDC

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.