Author: Jonathan Toomim 2015-12-18 02:47:14
Published on: 2015-12-18T02:47:14+00:00
On December 18, 2015, Pieter Wuille raised a concern about the risk of an old full node wallet accepting a transaction that is invalid to the new rules. In response, it was suggested that the receiver wallet chooses what address/script to accept coins on and upgrades to the new softfork rules before creating an address that depends on the softfork's features. However, the scenario presented by Mallory who wants to defraud Bob with a 1 BTC payment for beer, shows that there are potential vulnerabilities. Bob runs the old rules and creates a p2pkh address for Mallory to use. Mallory takes 1 BTC and creates an invalid SegWit transaction that Bob cannot properly validate and that pays into one of Mallory's wallets. Mallory then immediately spends the unconfirmed transaction into Bob's address. Bob sees what appears to be a valid transaction chain which is not actually valid. Clueless Carol, one of the 4.9% of miners who forgot to upgrade her mining node, sees that Mallory included an enormous fee in his transactions and includes both transactions in her block, allowing Mallory to get free beer.
Updated on: 2023-06-11T02:21:51.044999+00:00