Transaction is finalized before I sign (Potential issue)

[elRaulito]

I am signing a multisignature and as you see I am able to get the transacion ID and the finalized raw tx before I approve my signature, this means that signTransaction() function doesn't wait for me to sign and could potentially be exploited by someone who tries to make me sign a bad tx

I don't sign but anyway it was done and could be propagated by attacker

A bit more of details

• Signer 1 signs
• Signer 2 is asked to sign but transaction is already completed signed as soon as the prompt arrives, no need of my confirmation

[victorkirov]

Hi

Could you please provide a bit more details? How is the dapp getting the signed PSBT before the user clicks on confirm? Is the callback firing with a signed PSBT?

[elRaulito]

There are two parties

Alice Signs a PSBT where one input is multisig Bob is asked to sign the PSBT but as you see I am able to get the PSBT signed as soon as I fire the signTransaction() call

Therefore I can finalize, get the rawTx, the txid

All things should not happen until I sign

[elRaulito]

Nevermind, my bad

I was passing over to Alice a PSBT already signed by Bob, therefore as soon as I got it back i was able to finalize it

[victorkirov]

Haha. Cool. Thanks for the adrenaline spike 😉