It's been a while since I've updated this topic but yesterday the mempool grew and with it the fees went up. Which is a normal thing when price volatility increases but when looking at how it all increased, things look start looking suspicious.
[Speculation]In a natural mempool size growth we don't have a straight line because not everyone jumps on board of sending transactions at the same time specially not for a long period of time. It happens in "bursts", in other terms there should be a lot of different rates in the chart. Like this picture of a small rise from earlier this month.
However in a spam attack the attacker injects a large volume of spam transactions into the mempool usually at a fixed rate so the chart looks like the following picture which is from Nov. 14 to 15 over ~8 hours:
(Note that the
count chart also shows the same thing but not as cleanly since with each new block the count drops but the "slope" is fixed which points to the fixed rate at which transactions entered mempool).
From there, it's just a matter of keeping the mempool full and preventing it from going back down to keep the fees up while avoiding a larger cost on the spammer (due to ever rising fee if the spam rate was sustained). Usually regular users do most of the work there and the spammer doesn't have to spend much:
