[RL_Quine]

All miners connect to pools using a protocol called stratum. This is JSON piped over TCP with newline terminations. There is no authentication for this protocol and no encryption. You can simply intercept the communication here and have all the miners on a pool actually mine for your replacement pool, and nobody will ever catch on until its far too late.

> If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses.

That's not correct in practice. There's no authentication of the work going to the miner at all, so an attacker can just change the destination before the miner even sees the work.

[aphextim]

When I was toying around with mining some alt coins with GPUs a few years back I had the thought when joining a mining pool on say supernova, what is to prevent someone from doing an attack and convincing the pool to send my coins to them instead at a level 'under the hood' and beyond my understanding. Or get the entire pool to act in a way that is for their own personal gain.

I know there had been guides on how to set up your mining rigs, setup the batch files etc. These were all guides written by other people and I could see how in this newly created space there was room for nefarious actors to try to convince people to mine in a pool, but not give them the rewards they deserved or scammed them in some other way.

I also thought about someone hacking entire pools' hash-rates to be used for their own purposes rather than trying to figure out the next block on whatever chain it was running. This would allow someone to 'steal' the hash power of expensive rigs and redirect the power to their own wallets.

My understanding of all these protocols is very limited to what is regurgitated from others. When it comes to reading the bitcoin whitepaper I was only able to comprehend up until section 11 on page 6 where it got into the calculations, at which point I got lost as I am not that good at math.

Thank you for the insight.

[hinkley]

If you kept all of the coins from a pool, you'd be caught.

But would I ever know if you lied about the pool's GH/s rate and kept half of the coins?

[RL_Quine]

You can probably assume that most pools are skimming or cheating in some way, they'd never be caught.

[labawi]

Not going to claim they aren't skimming, but is it not possible to calculate expected number of blocks from declared GH/s, expected earnings from user provided MH/s and tell if the pool is excessively "unlucky"?

[hinkley]

Yeah I thought of that too after posting. I think it comes down to how transparent the pool is with their data.

The obvious thing to do would be to tell everyone that my 500 GH/s pool is 400 GH/s, and reward everyone an 80% share on every hash. If you're sophisticated enough you might notice that my pool is mining blocks about 25% above what you'd expect, but how many data point do you need for that, and it's statistical, so I'll have runs of good or bad luck.

Another option is to dilute the pool of contributors, but again you might be able to detect that either I'm misreporting your hash rate, or the sum of all contributions doesn't line up.

Assuming I give you enough tools to figure any of this out.

[labawi]

If you report the pool's hash rate as lower, the users should demand a higher fair share, as they know their own hash rate.

Either way, if a user knows his hash rate, he can calculate expected earnings and their presumed share. You could fudge a bit, but go too much, especially on a large pool, and it will be apparent. There are probably lots of users doing calculations, willing to call you out.

[SilasX]

Okay I see what you mean about replacing the work assignments going to the miners -- if you could tell them to solve a different block/fingerprint (hash of new block + previous block) and receive their output, then you can steal their hashing power. But I'm still not sure what you mean here:

>>If you mean the traffic of mining pools communicating their solutions to the pool's "mother brain", those are already cryptographically attached to a solution that pays out to specified addresses.

>That's not correct in practice. There's no authentication of the work going to the miner at all, so an attacker can just change the destination before the miner even sees the work.

I was referring here to the solutions the miners send out. That does not need to be authenticated because it's already attached to the block they were solving for -- i.e. it is a proof of work valid only for a specific block. If they received the correct block and nonce range to check, then the solutions are useless to anyone else. Diverting their traffic would just reduce the mining pool's hash power, not give it to anyone else.

So yes, I see how you could steal the miner's hash power if you could replace the assignment the pool head was giving them, and then see the output, but I don't think it's correct to say that solutions are vulnerable to being stolen after getting the correct assignment "because they don't authenticate" -- the proof of work is only valid for that block, and so could only be destroyed, not stolen.

[RL_Quine]

You're fundamentally missing the point somehow.

When you connect to a pool, you give them absolute trust over what you're mining using your hardware with the expectation that they will pay you for it later. In a route hijack, an attacker can replace the pool and announce their own work to you, and receive all results you produce. You can not distinguish this with the normal behavior of the pool and will be robbed, and your work can be used to do whatever the attacker wishes.

The output of the work being loosely "authenticated" with the pool by virtue of the work being non-transferable is entirely orthogonal. Nobody is going to be taking that because it's worthless, as you correctly point out. They're going to replace the work that's sent to you in the first place, because that's what makes sense.

[SilasX]

Pretty sure I'm not missing the point, because that's exactly what I said, in different words.

I specifically agreed that, if you can replace the assignment given to the miners ("replace the pool and announce their own work to you"), and see the output, then you can steal the work. It was in this paragraph:

>>Okay I see what you mean about replacing the work assignments going to the miners -- if you could tell them to solve a different block/fingerprint (hash of new block + previous block) and receive their output, then you can steal their hashing power.

That is an agreement with your:

>In a route hijack, an attacker can replace the pool and announce their own work to you, and receive all results you produce.

That is me communicating agreement that that's the attack that "makes sense" as in your sentence here:

>They're going to replace the work that's sent to you in the first place, because that's what makes sense.

I made my original because it sounded like you were saying a miner not (separately) authenticating their output to the pool would be an issue, which I now see you (always) agreed is orthogronal; my only objection in the follow-up was that your comment was addressing something different than I originally raised:

>>>That's not correct in practice. There's no authentication of the work going to the miner at all, so an attacker can just change the destination before the miner even sees the work.

>>I was referring here to the solutions the miners send out.

So, if I agree with you on every question of what and where the threat is and is not, and said so with slightly different words than you did, what point do you think I'm fundamentally missing?

[DoctorOetker]

(I am not informed about what the typical arrangement is to spread out the stochastic reward a pool earns over its members, so I am making no claims on this front)

But if the (non-principled) value of mining 20 blocks is 20 block rewards, then there we have the cost of buying 20 blocks (assuming miners non-ideologically sell out).

Assume they would not voluntarily sell out, then any flaw in the pooling mechanism (by which miners dilute the rewards into a steady income) which allows 1) other work to be assigned to the miner 2) while still receiving their intended addresses, would allow an attacker who is able to hijack the work assignments, to buy those 20 blocks for the price roughly on the order of ~ 20 block rewards, by 1) hijacking the work assignments 2) payout out the miners the correct expected amounts so that they hopefully don't notice

Is that correct?

[labawi]

> You can simply intercept the communication here and have all the miners on a pool actually mine for your replacement pool, and nobody will ever catch on until its far too late.

Depending on what you consider fat too late, doesn't the pool verify the solutions, and provide OOB statistics, where people would notice over time that they get 0 credits?

[RL_Quine]

Yes. The response time to that will be much less than the time to perform an attack with that hash rate though. We’ve seen people mine for literally 4 months on a broken pool that produced no income before they noticed.