That's what makes it impossible to trick someone logging into a dapp to actually sign a valid Ethereum transaction. 

Transactions are prefixed with single byte values:

0x01 - 2930 tx
0x02 - 1559 tx
0x03 - 4844 tx

more info here: https://github.com/ethereum/execution-specs/tree/master/lists/signature-types

I thought this was the attack that people in the NFT world keep (kept?) falling for. If not, how is it that they keep getting their wallets drained?

Pragmatism (Security) at OP Labs.
Prev: ConsenSys & Coinbase.

Attribs: Friendly, curious, introverted, mid-witted.
Chans: /eth-security /maurelian /stoicism




co founder of @metamask . Making computers behave for us.

Thanks! And what is the thing that usually creates the tx for them to sign? A scammy dapp?

ERC-1155 setApproveAll. The only nft allowance method in that interface.

It's similar, I think the common one is signing approval for an NFT collection without realizing it, then the approved address can suggest a txn which sends them your BAYC.
But people do far dumber things too.