Subnostr

#asknostr #bitcoin #plebs do you understand the #lightning vulnerability called the #replacement-cycling attack?

TLDR; it is a REAL vulnerability and funds CAN get stolen!

In the lightning network, transactions are send while being abscent on the blockchain: in order to still have security, every channel requires a secret pass from both users, say, Alice and Bob.

To change the balance in the channel, the initiator has to publish the previous secret to create a new one. If Bobs payment is malicious, Alice can use Bobs own past secret against him to retrieve all funds in the channel (stored on-chain and requires on-chain transactions). This has to happen in a short time: a day. Otherwise the attacker can still succeed in stealing all funds. Normally, this is enough to disincentivise hackers from ever trying.

Unless...

And this is where the vulnerability is so critical: it allows hackers to delay Alices transaction, up until it is too late for her to get refunded. They do this by replacing her transaction to get refunded by another "version" with a higher fee, so that Alices transaction gets ignored.

If everyone helps think of a solution, we could maybe solve it.

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Discussion

₿itcoin 2y ago

In the end, it boils down to this:

Alice must be fast to make a "counter offensive" transaction against the attacker, which can never be guaranteed because transactions can always be ignored.

Thus, in order to solve this, time should not play a role in security (in this context). Can we come up with another solution for securing the lightning network?

₿itcoin 2y ago

It is really difficult (potentially costly) to utilize this vulnerability(but maybe not for governments).

migitating this attack can

by rebroadcasting your redeeming transaction many times with higher fee. This forces them to create a new transaction with higher fees.

by looking for certain transactions in order to know as fast as possible if someone is trying to tamper with you.

₿itcoin 2y ago

To completely solve it there are some proposals (some requiring consensus) that change the way the channel contract is set up.

also watching nodes and not accepting channels under cerain rules helps migitae this attack.

I am not very very knowledgable in this mater, search also for yourself about this issue.