01 / Attack path
How the boundary is crossed
A transfer times out after the bank accepts it, and the agent automatically submits the same payment again.
- 01Lower-trust input
- 02Attempted instruction
- 03Protected action
- 04Enforced decision
02 / Containment
Where bounded authority limits the effect
Use a stable business-operation idempotency key, reconcile uncertain status before retry and reject changed arguments under the old key.
03 / Failure and evidence
The attacker’s opportunity and the defender’s record
A transport timeout is treated as proof of failure even though the first transfer committed.
Record both attempts, shared key, bank references, original decision and final settlement.
04 / Canonical scope
Why this reference stands alone
Idempotent agent actions describes the implementation contract; this threat traces duplicate-effect exploitation.
Protocol or attack trace
Unknown-outcome retry
Payment call times out after bank commit; agent submits retry with a fresh key.
Reconcile original transaction or reuse stable key; never create second transfer from transport timeout alone.
Primary references