The privacy-focused cryptocurrency Monero has recently experienced a significant disruption, with 60 mined blocks discarded from its blockchain within the past 24 hours. This incident is linked to an ongoing attempted 51% attack by the Qubic network.
The Monero Consensus Status dashboard reports that Monero witnessed 60 orphaned blocks—valid blocks that were rejected—in the last 720 blocks. This disruption coincides with an ongoing economic attack by the Qubic network, which incentivizes a practice known as selfish mining.
In this scenario, Qubic miners redirect their computing power to mine Monero (XMR) and subsequently sell the proceeds to purchase and burn Qubic tokens, earning payouts in QUBIC. Under this system, Qubic miners reportedly earn more than traditional Monero miners.
The attack has raised concerns of a potential “51% attack”—a rare and severe event that could allow attackers to rewrite transactions or block them entirely.
An orphaned block refers to a valid block that is excluded from the main chain because another competing block at the same height was accepted first. In selfish mining, a miner with significant hashrate withholds blocks and publishes them strategically to overtake the public chain, causing honest miners’ work to be discarded.
As of the time of writing, Monero’s price stands at over $247, marking a decline of over 8.6% from the price of over $276 reported 24 hours ago.
Monero’s 24-hour price chart. Source: CoinMarketCap
Qubic Attack Disrupts Monero Network
Qubic’s Monero mining pool is openly engaging in selfish mining. Sergey Ivancheglo, the founder of Qubic, admitted this in a social media post. Ivancheglo claimed in a Tuesday post that “Qubic has achieved 51% over Monero,” and the team is “waiting for independent confirmations.”
A 51% attack occurs when a single entity—in this case, the Qubic mining pool—controls over half of a blockchain network’s mining power or stake, enabling them to manipulate transactions. Zhong Chenming, co-founder of cryptocurrency cybersecurity firm SlowMist, noted in a Tuesday post that “this time the 51% attack on Monero seems to have succeeded.” He added:
“The cost was also high, and it’s unclear what the economic benefits of doing this are in the end… In theory, the Qubic mining pool can now rewrite the blockchain, achieve double-spending, and censor any transactions.”
Source: Zhong Chenming
Not Everyone is Convinced
Doubts persist regarding whether a successful 51% attack took place. Selfish mining with control over a high percentage of the hashrate that is short of the majority can sometimes lead to orphaned blocks.
Monero’s total hashrate evaluation by CoinWarz results in a 5 GH/s estimation. Unverified data from Qubic claims a peak hashrate of 3.01 GH/s, which is more than sufficient, and a current hashrate of 2.08 GH/s, insufficient for a 51% attack.
The Monero Consensus Status also indicates that the number of blocks mined by unknown mining pools and solo miners— a category that includes Qubic—reached nearly 30% on Aug. 11. This could signal Qubic controlling most of the hashrate for a brief period or controlling a significant portion but still a minority of the hashrate.
Luke Parker, lead developer at SeraiDEX, raised an issue with reports of a 51% attack in a separate post. He noted that a six-block-deep network reorganization with block orphaning “does not mean a ‘51% attack’ was successful.”
“It does mean an adversary with a high amount of hash got lucky,” he added.
Hack War Escalates Between Networks
Qubic and Monero are engaged in an ongoing hack war, trading countermeasures. Ivancheglo previously wrote that Monero broke Qubic’s selfish mining system, prompting his fix. Before this, Ivancheglo accused Sergei Chernykh, a developer of Monero mining software XMRig, of conducting a denial-of-service (DDoS) attack on Qubic’s pool, resulting in hashrate losses—a claim Chernykh disputes.
The attack originated in late July when the community noticed what it described as an “economic attack.” The operation uses economic incentives—paying Qubic miners more than Monero miners—in an attempt to take control over most of Monero’s hashrate and consequently the network.
Niko Demchuk, head of legal at on-chain forensics firm AMLBot, told Cointelegraph that Qubic’s attack on Monero could be deemed “computer sabotage” or “unauthorized access” under Belarusian and European Union laws. However, no statute explicitly mentions 51% attacks. Demchuk noted that Belarus’ cybercrime rules could apply if blockchain manipulation disrupts protected systems.
For more details, visit the original source: Cointelegraph.
