Bitcoin Forum

Ethereum $ETH▲1.15% Classic, one of the most popular forks of the second most valuable cryptocurrencies by market cap has suffered a 51-percent attack.

After Chinese blockchain security firm SlowMist raised the alarm, an analyst at CoinNess dug a little deeper. The analyst found that a private mining pool had managed to increase its hash power to 3,263 GH/s, making it – temporarily – the most powerful mining pool at around 11:00am UTC on 6 January.

After this brief spike in power, the mining pool returned to its normal state of around 300 GH/s. However, ten hours later the same thing happened again, and the pool’s hash rate began to climb. At the time CoinNess’ article was published the illicit mining pool’s power equated to around 63-percent of the total network hash rate.

Shortly after these attacks Coinbase paused all Ethereum Classic transactions, it initially detected that around 88,500 ETC ($460,000) had been double-spent. However, the cryptocurrency exchange has since uncovered another 12 attacks that “included double spends, [now] totaling 219,500 ETC ($1.1 million).”

<snip>

This is a thought-provoking observation. 🤔

By definition, a decentralized cryptocurrency must be susceptible to 51% attacks whether by hashrate, stake, and/or other permissionlessly-acquirable resources.

If a crypto can't be 51% attacked, it is permissioned and centralized.

This is a result of weak POW network. The number of participants in network is small enough to be manipulated by hackers. And almost altcoins have to face this problem.

Well, most other coins actually have measures in place to protect them against 51% attacks.
Yesterday, I saw a post on /r/cryptocurrency that stated it would only cost two times the attack cost of the ETC attack, to bring down the BCH network.

As much as I dislike BCH, this was factually incorrect, since BCH has a rolling block checkpoint system to prevent this.
https://blog.bitmex.com/bitcoin-cash-abcs-rolling-10-block-checkpoints/

Other coins also have measures against 51% attacks, here are some examples:
https://www.reddit.com/r/Monero/comments/896kjt/about_51_attack/

https://dailyhodl.com/2019/01/08/the-true-cost-of-51-attacks-on-bitcoin-ethereum-xrp-bitcoin-cash-litecoin-and-the-crypto-verse/

I haven't seen this news yet in Altcoin Discussion, so I thought I'd share the article here.
Hackers have stolen 1.1 million USD on Coinbase by doing double spends, after they'd gotten control of more than 50% of the mining hashrate.


Source: https://thenextweb.com/hardfork/2019/01/08/ehtereum-classic-51-percent-attack/

At least 14 double spends were detected!

This is bad not just for Ethereum Classic but for all of the cryptocurrency out there, that they actually still has one big flaw. The fact that it can overhash the 51% of the Ethereum Classic POW that we all know it is not a small POW network, it means most of other cryptos might be able to be attacked too. And the worse thing is that, this attack happen when crypto are about to recover from bear market, I hope it will not affect much.

that really is not good news for ethereum classic. i wonder what will happen next to the blockchain after this attack. i could almost imagine that could be the end of ethereum classic.  :(

I haven't seen this news yet in Altcoin Discussion, so I thought I'd share the article here.
Hackers have stolen 1.1 million USD on Coinbase by doing double spends, after they'd gotten control of more than 50% of the mining hashrate.

I haven't seen this news yet in Altcoin Discussion, so I thought I'd share the article here.
Hackers have stolen 1.1 million USD on Coinbase by doing double spends, after they'd gotten control of more than 50% of the mining hashrate.


Source: https://thenextweb.com/hardfork/2019/01/08/ehtereum-classic-51-percent-attack/

At least 14 double spends were detected!

This is the main reason why COINBASE delisted ETHEREUM CLASSIC on their wallet.
This must be fix soon before they will get back it. i hope that everything will be fix and get back to normal as ETC is a good one.

Thats impossible to fix in my opinion. The blockchain got manipulated because of the attack. A PoW based chain cant be protected from 51% attacks I think!

But the developer team of Ethereum Classic said that absolutely no 51% attack occurred. However, after having a double withdrawal order on January 5 on Coinbase, they proceeded to suspend the withdraw and deposit ETC. I think that happened 51% attacks

Researchers from crypto exchange Gate.io report they have confirmed that a 51 percent attack successfully occurred on the Ethereum Classic (ETC) blockchain. The company published an analysis of their findings Jan. 8.

Gate.io Research has published its analysis of ETC transactions on its platform during the alleged attack, claiming it has detected seven rollback transactions — four of which were reportedly conducted by the attacker, transferring a total of 54,200 ETC in total (worth $271,500 at press time).

Gate.io reports that the incident occurred over a period of 4 hours between 0:40 and 4:20 Jan.7, 2019 UTC, during which the transactions were normally confirmed on the blockchain and then subsequently invalidated after the malign network rollback. After providing details of three ETC addresses purportedly used by the attacker, Gate.io continues to explain:

    “Gate.io's censor successfully blocked [the] attacker's transactions at the beginning and submitted them to [a] manual exam. Unfortunately, during the 51% attack, all the transactions looked valid and confirmed well on the blockchain. The examiner passed the transactions. It caused about 40k ETC loss due to this attack.”

Gate.io states it will compensate its users’ losses, stating “Gate.io will take all the loss for the users.” The exchange also advises other crypto trading platforms to block transactions stemming from the identified suspect addresses. The exchange also states it has raised its ETC transaction confirmation number to 500 and launched a more robust 51 percent detection security mechanism.

Today, Jan. 9, Chinese blockchain security firm Slow Mist also published a report also confirming a 51 percent attack and containing and the same rollback transactions reported by Gate.io.

As previously reported, several major crypto exchanges — United States-based Coinbase and Japanese exchanges bitFlyer and Coincheck — have have all temporarily suspended withdrawals and deposits of ETC as early as Jan. 5. The exchanges all reportedly moved to respond to unusual hashpower activity indicating a potential 51 percent attack, as well as Coinbase’s own findings of double spending and “chain reorganizations.”

The ETC dev team initially responded by refuting that a 51 percent attack had taken place, stating that double spends had not been detected. At the time, they claimed that majority control over the network’s hashrate was “most likely selfish mining,” attributable to the testing of new 1,400/Mh ethash machines by application-specific integrated circuit (ASIC) manufacturer Linzhi.

As reported, a 51 percent attack can occur on blockchains that use a proof-of-work (PoW) algorithm, and essentially entails a user or group seizing control of the majority of mining power to monopolize control over the network. This, in particular, can allow the threat actor to reverse transactions with the view to double spend — by transacting crypto for fiat currency, and then rolling back the deed to recuperate the spent crypto, while pocketing the fiat.

While the theoretical risk of majority attacks exists, practically seizing control of a large hashrate blockchain is widely considered to be prohibitively expensive at present. The PoW-based Bitcoin blockchain has not to date been compromised by a hijack of the network’s hashrate, but some developers have nonetheless made the case for investigating potential PoW change.

I haven't seen this news yet in Altcoin Discussion, so I thought I'd share the article here.
Hackers have stolen 1.1 million USD on Coinbase by doing double spends, after they'd gotten control of more than 50% of the mining hashrate.


Source: https://thenextweb.com/hardfork/2019/01/08/ehtereum-classic-51-percent-attack/

At least 14 double spends were detected!