Quote from: JayDDee on April 19, 2021, 10:50:32 PM

What you describe is impossible, each stratum connection only accepts hash produced
from the unique data it sent. It's invalid for any other stratum connection.

If the etherbase (for pplns and solo pools) is the same, then everything else - demon, task - is the same too. This is easy to check in explorer.
Next, you must specify which version (and implementation) of the EthereumStratum do you mean. Ethereum is a patchwork quilt and your declaration looks too bold. EthereumStratum != BTCStratum.

For Bitcoin, yes, this is a coinbase field problem what including extranonce. In the EthereumStratum v1 (v2 is not actually used) there are many more possibilities to manipulate this parameter. Many pools do not provide extranonce at all, using Id & job ID only.
Rest data can be easily swapped on the fly - this device contains a high-speed FPGA specialized in telecommunications.
During pplns retransmission, device can lazily palpate the both pools and choose the best hole (requests to change various parameters in the simplest case). This is not a stupid relay, it has advanced logic which is noticeable from the element base. For typical MITM it is overkill.
If it is impossible to work with this pool(s), it will signal. But on the verge of POS, no one is in a hurry to close vulnerabilities...

I am testing known BTCStratum vulnerabilities for now and I am not claiming btc at this stage. Stratum V2 looks much more promising for BTC switch.

P.S. Why should I infect my own device?