Time-locked Bitcoin transactions allows miners to steal bitcoins from each other

• A vulnerability may become more dangerous over time.
• The solution is already developed but the implementation will take time.

Over a million of time-locked Bitcoin transactions between September 2019 and March 2020 were misconfigured. This bug made them vulnerable to hack attach with the aim to steal cryptocurrency. The bug affects 2% of all transactions in the Bitcoin network, according to a study berformed by the developer aka 0xb10c.

Time-locked transactions prohibit the recipient from using bitcoins as soon as they are deposited. They have to wait until a certain condition is reached. For example, a timelock can be configured to expire when a certain number of blocks are added to the network, or at 
an approximate point in the future.

The time-locked transactions have many use cases. For example, Blockstream uses themto pay salaries to its employees, thereby encouraging them to be more productive. The personal wealth of developers is directly related to the long-term value of the entire network.

0xb10c detected an array of time-locked transactions set up on the current block. Such transactions make it less profitable to use malware for mining, focused on spoofing blocks and transactions to steal commissions.

Currently, not enforcing a timelock to an absolute block height does not have consequences for the majority of transactions. In a few years, when the block reward consists mainly of transaction fees, it might make fee-sniping more profitable, 0xb10c told CoinDesk.

The researcher explained that the solution had been developed at the beginning of the year, however, the full implementation would take time.

0xb10c found out that the vast majority of these transactions were sent by one party, which he did not disclose.