# OAM Failure Modes

## Secure Packet Transfer Integrity Stack v0.1

OAM is used here as a degradation and hard-fault diagnostic layer. It identifies where packet-transfer claims can fail under pressure.

## Failure modes

### 1. Payload mismatch

The destination payload does not match the source payload under verification.

- Primary pressure: `payload_fidelity_failure`
- Likely state: RED
- Example signals: hash mismatch, corrupted payload, unexpected transform, partial transfer.

### 2. Replay pressure

Old, duplicated, or captured traffic is presented as valid.

- Primary pressure: `replay_pressure`
- Likely state: RED if detected or anti-replay protection fails.
- Example signals: reused nonce, invalid sequence, duplicate signed packet, timestamp anomaly.

### 3. Downgrade attempt

A stronger protocol, cipher suite, setting, or protection state is weakened without authorization.

- Primary pressure: `downgrade_attempt`
- Likely state: RED
- Example signals: negotiated weaker version, forced fallback, policy mismatch.

### 4. Man-in-the-middle pressure

An intermediary attempts to observe, alter, impersonate, or redirect the session.

- Primary pressure: `mitm_pressure`
- Likely state: RED when identity/session verification fails; YELLOW when unresolved anomaly remains.

### 5. Certificate / key failure

The transfer depends on identity material that is stale, invalid, revoked, mismatched, weak, compromised, or unverifiable.

- Primary pressure: `certificate_failure` or `key_compromise`
- Likely state: YELLOW or RED depending on policy and severity.

### 6. Route/session drift

The route or session behavior changes in a way that creates uncertainty or integrity pressure.

- Primary pressure: `route_hijack` or `route_session_drift`
- Likely state: YELLOW unless identity/session evidence fails, then RED.

### 7. Metadata leakage

Payload may remain protected while metadata leaks more than the boundary permits.

- Primary pressure: `metadata_leakage`
- Likely state: YELLOW or RED depending on sensitivity and policy.

### 8. Endpoint compromise

The transfer protocol succeeds, but one endpoint is degraded, malicious, or already compromised.

- Primary pressure: `endpoint_compromise`
- Likely state: RED if confirmed; YELLOW if suspected.

### 9. Audit-chain break

The evidence chain is incomplete, discontinuous, tampered, missing, or unverifiable.

- Primary pressure: `audit_chain_break`
- Likely state: RED or downgraded claim state.

## OAM rule

A transfer cannot be upgraded beyond the evidence boundary. If audit continuity fails, claims must downgrade even when delivery appears successful.