51% of

The developers of Ethereum Classic, who initially denied a 51% attack on the network of this cryptocurrency, recognized this fact on Monday evening, suggesting that it turned out to be connected with testing new miners.

The first reports that 51% of the Ethereum Classic is under attack came on Monday night, but the project’s representatives initially denied it. So, in a tweet published last night, they claimed that the network was working normally and that there was no such information in the “Reorg” section of the BlockScout website.

There have been a possible chain reorganization or double spend attack.

From what we can tell the network network operating normally.

BlockScout's "Reorg" section. https://t.co/Yi2cXusCz9 pic.twitter.com/HdUtS0DJZK

– Ethereum Classic (@eth_classic) January 6, 2019

Nevertheless, this information appeared later on this resource, after which the ETC developers appealed to the stock exchanges and the mining pool to increase the number of transaction confirmations when withdrawing funds and accepting deposits at least to 400.

To all exchanges and mining pools, please click here.

cc from @OKEx @ExchangeXGroup @HuobiGroup @digifinex @binance @bitfinex https://t.co/m5cxcKBVXa

– Ethereum Classic (@eth_classic) January 7, 2019

At the same time there were reports that the notification of problems in the Ethereum Classic network was distributed by the Chinese company SlowMist. The unusual growth of the ETC hashrate was due to the activity of the unnamed private mining pool.

As can be seen in the graph below, at a certain point on Monday, the ETC hashrate exceeded 10 Th / s, although most of the first week of January was at levels below 8.5 Th / s.

Source: coinwarz

And only on Monday evening, the Ethereum Classic team announced that it had found a plausible explanation for what had happened. According to them, ASIC miners Linzhi Shenzhen, who allegedly had already confirmed that he was testing new devices for the Ethash algorithm with 1,400 / Mh, was to blame for everything.

Regarding the recent mining events. We have an idea of where it came from.
ASIC manufacturer Linzhi confirmed testing of 1,400 / Mh ethash machines #projectLavaSnow
– Most likely selfish mining (Not 51% attack)
– Double spends not detected (Miner dumped bocks)

– Ethereum Classic (@eth_classic) January 7, 2019

Also, representatives of Ethereum Classic insist that this is not about an attack of 51%, but rather about the so-called mercenary mining, and that there have been no cases of double spending of coins.

However, not everyone agrees with them. So, Coinbase Exchange wrote in its blog that the deep reorganization of the blockchain Ethereum Classic was noticed on January 5th, as a result of which double spending was carried out. The exchange immediately stopped the movement of these funds, after which it recorded eight additional cases of chain reorganization. The total amount of 51% of the funds hit by the attack, according to Coinbase, was 88,500 ETC (about $ 460,000).

On 1/5/2019, Coinbase detected. In order to protect customer funds, we’ve taken a blockchain. Read more here: https://t.co/vCx89dz44m

– Coinbase (@coinbase) January 7, 2019

Moreover, CoinDesk reporter Nihilesh De wrote on Twitter that Linzhi Shenzhen, manufacturer of miners mentioned by the Ethereum Classic team, denies any involvement in the incident.

UPDATE: Wolfgang Spraul refuted claims that he was involved in the reorg: “We’re categorically denying such claims, they’re not allowed.” Https://t.co.zM

– Nikhilesh De (@nikhileshde) January 7, 2019

“We categorically refute such allegations, they are completely baseless and can be part of the attack itself, ” said Linzhi Shenzhen’s operational director Wolfgang Sprouul.

CoinDesk also notes that since Sunday, more than 100 ETC blocks have undergone reorganization, according to the browser review of the Bitfly (Etherchain) and Blockscout blocks. At the same time, there is no consensus on the duration of the attack. So, if Blockscout reports that the incidents occurred at 02:00 UTC and 05:00 UTC on Monday, then Bitfly reported that, as of 17:00 UTC, the potential attack continued. Coinbase also claims a continuing attack.

51% attack on the Ethereum Classic ( #ETC ) network with multiple 100+ block reorganization. We highly recommend confirmations.

– Bitfly (@etherchain_org) January 7, 2019

Blockscout spokesman Andrew Craveno, meanwhile, said that although after the reorganization of the blockchain occurred more than 14 hours ago, "the network is constantly fluctuating and the hashrate is constantly changing." According to him, this creates "ideal conditions" for the continuation of network outages.

The director of ETC Cooperative, Anthony Lusardi, also cited data on reorganized blocks, noting that the additional hashrate actually appeared as if from nowhere and could potentially be associated with new ASICs.

Here you go, there were 8 that are> 75 blocks. The hashrate doesn’t seem to come from ETH miners nor Nicehash, appearing out of nowhere. Potentially new ASICs. https://t.co/kPrCAvlbW9

– Anthony Lusardi (@pyskell) January 7, 2019

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