GRIN 51% attack technical report - published

Running a big GRIN-Infrastructure allowed us to setup some GRIN-Chain monitoring solutions.

In coordination with the Grin-Council, we setup a “Block-Reorg monitoring system” for all our productive Grin-nodes. This service is not yet public, as we didn’t have the resources to implement this into our public API.

Details of the REORGs

  • REORG (blockchain reorganization) : A built-in feature of the Grin network designed to deal with the issue of simultaneously mined blocks.

  • REORG attack : A blockchain reorganization attack occurs when miners collaborate to remove previously confirmed blocks from the blockchain.

Scope of the upcoming report:

We are keeping it technical , no speculations no assumptions, even we did get in contact with and 2Miners

Link to the report:

last update: 09.11.2020 - 18:27 (UTC) view here

This report was co-written by deeev (Keybase).

Contact us here


78$ dollar to 51% attack for an hour… Shame of hackers… lol… Long live Grin


As an interim solution:
We have a community funded instance of the Grin NiceHash Defender bot.

Please spread the word. We need at least 0.01BTC to place minimum defensive orders on both EU and USA markets. runs it own instance of grindefender with own budget.


Do the mined Grin by the bot go back to the fund to keep sustaining the fund/defender as long as possible ?

To my knowledge, yes.
But this is not a project, grindefender was created by bladedoyle.

This topic should be put very visible in the Grin newsletter and be broadcasted on Twitter together with the link to the 51% attack report. In that way much more donations will come in, further boosting security.

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@lehnberg could you please add this to the next newsletter ?

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Long live Grin :grinning: