{
  "id": "ap1-approve-swap",
  "title": "The Token Approval",
  "extends": "m1-send-metamask",
  "context": {
    "wallet": "MetaMask extension",
    "platform": "Chrome extension",
    "network": "mainnet",
    "settings": "defaults",
    "version": "web/5.157.3",
    "observed": "2026-08-25",
    "captures": [
      {
        "run": "20260825-094249-approve-swap",
        "tx": "0x0befcc214f5a3a82a816913c5b0248c356ba7f770ee7174cd5df90e178e2ed48"
      }
    ]
  },
  "_comment": "The APPROVAL — the signature that drains wallets. To swap a token OUT (mUSD → ETH), MetaMask needs permission to move your mUSD. Unlike an ETH-input swap (M4), an ERC-20 input requires an allowance. Modern MetaMask grants it with PERMIT2: instead of a visible on-chain approve() transaction, you SIGN a typed-data permit locally (eth_signTypedData) — gasless, no separate tx, invisible in the mempool — and the signed permit is embedded in the swap calldata (real tx 0x0befcc…ed48 to MetaSwap, method swap, 0 ETH value, mUSD pulled via the permit). This is exactly the phishing vector: a malicious site asks for a Permit2/permit signature and drains the token, because a signature — not an obvious 'send' — is what grants the allowance. The wallet shows a swap; the allowance rides inside it. Same getQuoteStream engine and STX relay as M4.",
  "prepend_steps": [
    {
      "id": "approve-permit",
      "phase": "sign",
      "name": "Permit2 allowance — you SIGN it",
      "host": "(local Permit2 signature — no on-chain approve, no network call)",
      "actor": "self",
      "purpose": "Grant MetaMask's swap router permission to move your mUSD by signing an EIP-712 Permit2 permit — gasless, done locally, then embedded in the swap calldata",
      "need": "W",
      "carries": [
        "selected_address",
        "token_pair"
      ],
      "births": [
        "signed_tx"
      ],
      "returns": "an allowance the router can spend against — as large and as long-lived as the permit says",
      "can_block": false,
      "on_failure": "blocks",
      "failure_note": "no permit → the router can't pull the token → no swap",
      "worst_lie": {
        "outcome": "funds_lost",
        "note": "THE drain vector: a permit signed for a malicious spender (or an unlimited amount) lets that spender empty the token later — and it's a signature, not a 'send', so it doesn't look dangerous"
      },
      "removable_by": "none",
      "tx_input": "field",
      "provenance": {
        "status": "observed",
        "ref": "20260825-094249-approve-swap · tx 0x0befcc…ed48 (Permit2 embedded in the swap calldata; no separate approve tx and no network request for the signature)"
      },
      "notes": "Signed locally on your device — the danger isn't who receives it, it's what you authorized. Phishing sites request exactly this signature.",
      "fixed_by": [
        "clear-signing"
      ]
    },
    {
      "id": "swap-quote-out",
      "phase": "discover",
      "name": "MetaMask swap engine · route + calldata",
      "host": "bridge.api.cx.metamask.io/getQuoteStream",
      "actor": "consensys-apis",
      "purpose": "Same closed engine as M4 — returns the route, minimum-out, fee, and the swap calldata (which carries your signed Permit2 permit)",
      "need": "RC",
      "carries": [
        "ip",
        "selected_address",
        "token_pair",
        "amount",
        "holdings"
      ],
      "births": [
        "unsigned_tx",
        "swap_route"
      ],
      "returns": "the price you act on and the bytes you sign",
      "can_block": true,
      "on_failure": "blocks",
      "worst_lie": {
        "outcome": "funds_lost",
        "note": "one closed API sets the route, the minimum-out, and the calldata your permit authorizes"
      },
      "removable_by": "none",
      "tx_input": "field",
      "provenance": {
        "status": "observed",
        "ref": "20260825-094249-approve-swap · GET bridge.api.cx.metamask.io/getQuoteStream"
      },
      "fixed_by": [
        "verifiable-rpc"
      ]
    }
  ],
  "own_node": {
    "node": "192.168.68.54",
    "runs": [
      "20260924-214113-approve-swap-localnode"
    ],
    "steps": {
      "approve-permit": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "swap-quote-out": {
        "state": "out",
        "ref": "bridge.api.cx.metamask.io · 2 req after switch · /getquotestream"
      },
      "ext-update": {
        "state": "unseen",
        "ref": "clients2.google.com seen before the switch only, not after"
      },
      "feature-flags": {
        "state": "out",
        "ref": "client-config.api.cx.metamask.io · 1 req after switch"
      },
      "phishing-list": {
        "state": "unseen",
        "ref": "phishing-detection.api.cx.metamask.io seen before the switch only, not after"
      },
      "c2-list": {
        "state": "unseen",
        "ref": "client-side-detection.api.cx.metamask.io seen before the switch only, not after"
      },
      "token-list": {
        "state": "out",
        "ref": "token.api.cx.metamask.io · 1 req after switch"
      },
      "spot-prices": {
        "state": "out",
        "ref": "price.api.cx.metamask.io · 6 req after switch · /v3/spot-prices"
      },
      "fiat-rates": {
        "state": "unseen",
        "ref": "price.api.cx.metamask.io still contacted (6 req) but this exact call wasn't singled out"
      },
      "accounts-balances": {
        "state": "out",
        "ref": "accounts.api.cx.metamask.io · 3 req after switch · /v4/multiaccount/balances"
      },
      "balance-fallback": {
        "state": "local",
        "ref": "192.168.68.54 · eth_call; mainnet.infura.io got 0 after switch"
      },
      "nft-detection": {
        "state": "unseen",
        "ref": "nft.api.cx.metamask.io seen before the switch only, not after"
      },
      "defi-positions": {
        "state": "unseen",
        "ref": "defiadapters.api.cx.metamask.io seen before the switch only, not after"
      },
      "icons": {
        "state": "out",
        "ref": "static.cx.metamask.io · 1 req after switch"
      },
      "block-poll": {
        "state": "local",
        "ref": "192.168.68.54 · eth_blockNumber; mainnet.infura.io got 0 after switch"
      },
      "segment": {
        "state": "out",
        "ref": "api.segment.io · 4 req after switch"
      },
      "sentry": {
        "state": "out",
        "ref": "sentry.io · 15 req after switch"
      },
      "screen-recipient": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "nonce": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "gas-fees": {
        "state": "out",
        "ref": "gas.api.cx.metamask.io · 3 req after switch · suggestedgasfees"
      },
      "estimate-gas": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "simulation": {
        "state": "out",
        "ref": "tx-sentinel-ethereum-mainnet.api.cx.metamask.io · 2 req after switch"
      },
      "security-alert": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "stx-broadcast": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "inclusion": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "stx-status": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "receipt-poll": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "etherscan-check": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "balance-refresh": {
        "state": "unseen",
        "ref": "accounts.api.cx.metamask.io still contacted (3 req) but this exact call wasn't singled out"
      }
    },
    "unmapped": [
      "tron-mainnet.infura.io",
      "solana-mainnet.infura.io",
      "bitcoin-mainnet.infura.io",
      "user-storage.api.cx.metamask.io",
      "monad-mainnet.infura.io",
      "subscription.api.cx.metamask.io",
      "api.merkl.xyz",
      "carrot.megaeth.com",
      "testnet-rpc.monad.xyz",
      "linea-sepolia.infura.io",
      "sepolia.infura.io",
      "polygon-mainnet.infura.io",
      "optimism-mainnet.infura.io",
      "bsc-mainnet.infura.io",
      "arbitrum-mainnet.infura.io",
      "base-mainnet.infura.io",
      "linea-mainnet.infura.io",
      "notification.api.cx.metamask.io",
      "geolocation.api.cx.metamask.io",
      "on-ramp-cache.api.cx.metamask.io",
      "tokens.api.cx.metamask.io",
      "authentication.api.cx.metamask.io",
      "metamask.github.io",
      "cdn.contentful.com",
      "gateway.api.cx.metamask.io"
    ]
  }
}