It might seem like science fiction that the oldest blockchain ever was attacked or suffered a problem, but that's exactly what happened to block 666833 as they managed to spend 0.00062063 BTC:
Before going into the news, it is necessary to take a step back and explain that the bitcoin network manages the blocks sequentially and that the blocks have the hash of the previous block, and obviously also the data, i.e. the transactions contained within. of the block, and everything is governed by the Proof of Work (PoW) consensus protocol.
This may be sufficient but it is not, because since there is an adjustment on the difficulty of the protocol, then it can happen that many miners join the network all together, and therefore increase the number and height of the block too much. fast, and so vice versa, and to solve this type of problem, every about 2 weeks, the difficulty is adjusted, and since a time unit is introduced, then on the bitcoin blockchain the timestamp that examines the time as a parameter and which serves precisely for this reason, we can consider this feature as if it were a distributed clock on blockchain.
Even if we have time unit, which in this case is both the timestamp that we find in the block and is set by the miner, and both the time that the block was actually produced, it is not certain that especially the timestamp coincides with the time of the block product, and therefore this could lead the miners to set a different and longer time so as to distort even the rewards that are recovered earlier.
In order for this mechanism not to be encouraged by miners and therefore to operate incorrectly, there are 2 mechanisms dedicated to protection:
- The MPT (Median Past Time) rule, i.e. that the timestamp must be higher than the median of the last 11 blocks, which in this case are 6 blocks, and therefore with a minimum confirmation of 6 blocks, and therefore reduce the risk that someone may having attacked the network;
- The Future Block Time rule, that in this case the timestamp cannot be more advanced than 2 hours in the future with respect to the constant MAX_FUTURE_BLOCK_TIME, and in addition the maximum time between the time provided by the node and the actual time of the machine must not exceed 90 minutes and therefore for timestamps too far into the future are automatically considered null.
And therefore, as can be seen from the image, there was a time lag in the timestamps that stalled the bitcoin network for a few minutes, almost 2 minutes, and thanks to this "indecision" of the network, to identify the most long, someone managed to spend that amount on the longest chain, in fact no RBF (Replace by Fee) was detected.
So in a nutshell bitcoin doubled for 2 minutes, which is not worrying because it then stabilized. However, there is no denying that the Bitcoin Blockchain was 'indecisive' for a grand total of 2 minutes.