Monero coin 51% Attack: A 3 billion takeover of 6 billion as a technical validation?

Written by: AIMan@Golden Finance

Did Qubic successfully execute a 51% attack on Monero?

As early as the end of July, the Monero community was circulating rumors that the QUBIC mining pool was attacking Monero. Now it seems that QUBIC has succeeded.

On August 12, 2025, Slow Fog tweeted that the Monero network (XMR) is suspected of undergoing a 51% attack. Recently, Monero experienced a chain reorganization of 6 blocks deep mined by an unknown pool. However, no pool on miningpoolstats holds more than 50% of the hash rate, so this could be a covert malicious hash power attack or an accidental mining competition.

At the end of July, during the QUBIC attack, the market capitalization of Monero was about 6 billion USD, and currently, the market cap of XMR is about 4.6 billion USD, having dropped over 20%. Meanwhile, the market cap of QUBIC is only about 2.3 billion USD. If QUBIC truly succeeds in controlling 51% of the Monero's hash power, we will witness a historic moment where a blockchain with a market cap of less than 300 million USD is taking over a blockchain with a market cap of 6 billion USD.

What exactly happened?

User OrangeFren posted that Monero has experienced a deep reorganization of 6 blocks. A 51% attack seems to have been successful. If you are receiving XMR, please wait at least 10 blocks.

Ledger CTO Charles Guilemet stated:

Monero seems to be undergoing a successful 51% attack. This privacy-focused blockchain was launched in 2014 and has long been a target for governments and three-letter agencies (note: FBI), and is now banned by most major centralized exchanges. The Qubic mining pool has been accumulating hash power for months and currently controls most of the hash power of the Monero network. This morning, a significant blockchain reorganization was detected. With its current dominance, Qubic can rewrite the blockchain, execute double-spends, and censor any transaction. The estimated cost to maintain this attack is as high as $75 million per day. While the potential profits are substantial, it could potentially destroy people's confidence in the Monero network overnight. Other miners have no incentive to continue the attack because Qubic can easily turn any competing blocks into orphaned blocks, making it the sole miner. In fact, a blockchain with a market cap of $300 million is taking over a blockchain with a market cap of $6 billion. Monero's options for recovery are limited, and a complete takeover has become possible, even quite likely.

X user Caffeinated User said:

Qubic has just achieved a 51% hash rate dominance over Monero. This is a huge feat. They will become the first to manipulate a cryptocurrency through a 51% attack. They plan to isolate all blocks from other miners, making themselves the sole mining entity for Monero. The only way to mine Monero is through them, and their profit is directly 3 times that of mining Monero. They will distribute half of the profits to miners, while the other half will be sold to buy QUBIC and sent to a burn wallet. If they mine 100% of the Monero blocks, they could mine 432 Monero daily. At the current price of Monero, this amounts to $118,342.08. They keep 50% of that, distributing the rest to miners, profiting $59,171.04 daily from Qubic's burn. They will burn $414,197.28 weekly and $1.656 million monthly. This is insane. This is a historic moment. Qubic, with a market cap of less than $300 million, will become the sole miner of a currency with a market cap of $6 billion.

The founder of Qubic, Come-from-Beyond, stated on social media: It seems that Qubic has achieved a 51% success rate, surpassing Monero, and we are waiting for confirmation from an independent agency. Meanwhile, the Monero team is refining the details of its 51% attack protection. Many people accuse us of receiving funding from some three-letter agencies to attack this anonymous coin. After we helped Monero prepare for future struggles against these agencies, what are your thoughts now?

Of course, there are differing opinions. User Luke Parker stated that 6 reorganizations do not mean a "51% attack" was successful. In this case, we would see other mining pools undergo infinite depth reorganization/no blocks being mined (assuming the opponent reviews other mining pools like this one). This does imply that the opponent with a high hash rate is quite lucky.

Is Qubic only for verifying technology and attracting attention?

First, let's understand Qubic.

Qubic was founded by Come-from-Beyond, a co-founder of the IOTA blockchain with a directed acyclic graph (DAG) architecture. Qubic is a unique L1 public chain, whose core mechanism is useful Proof of Work (uPoW) and AIGarth. Traditional mining usually boils down to solving arbitrary puzzles, while Qubic transforms computational power into actual productivity—training its AI model called AIGarth. The working principle is as follows: miners contribute their raw computational resources to Qubic's validators (called Computors). Then, these Computors use this computational power to directly train AIGarth in their memory, with all operations conducted on-chain.

The larger vision of Qubic is to provide outsourced computing for the real world, inviting third parties such as businesses, universities, hospitals, research laboratories, etc., to use AIGarth. Through customized smart contracts, these entities can connect and adjust models according to their own needs, even utilizing Qubic's computing network to train dedicated versions, much like opening a decentralized supercomputer to the world. Collaborators can contribute and benefit without compromising security. However, the complete version of this vision has not yet fully materialized, and key components (such as Oracle Machines for seamless data integration) are still under development.

To demonstrate the feasibility of outsourced computing in real-world environments, Qubic has come up with custom mining: Qubic provides computing power outside its network, redirecting part of Qubic's computing power to external tasks, such as mining Monero or other PoW cryptocurrencies. Qubic also states that the true potential of outsourced computing goes far beyond cryptocurrency mining.

At the end of July, Qubic began custom mining for Monero. Why start with Monero? The Qubic official stated that by entering the high-risk, competitive field of Proof of Work (POW) cryptocurrency mining, it not only validates technology but also attracts industry attention.

How is the effect?

The Qubic blog article shows that before the integration of Monero custom mining, CPU only accounted for 10% of Qubic's mining power. Due to the appeal of higher profitability, this number has surged to around 50% as more CPU miners flock to the network. During the week of July 30 to August 7, the peak mining power of the Qubic network reached 2.77 GH/s, accounting for 50% of the global Monero hash rate. A total of 4285 Monero blocks were discovered, mining approximately 517 XMR + 6M XTM. These XMR, worth about $141,658, were sold, with 50% used for Qubic coin buybacks and burns, and 50% used to incentivize miners to provide more CPU hash power. The Qubic official stated that for miners, Qubic's profitability is about three times that of Monero, which is why many CPU miners have joined the Qubic network.

During this period, the Monero community carried out a DDoS attack on Qubic, but the effect was not significant.

The founder of Qubic Come from Beyong stated on August 3rd that despite suffering from severe DDoS attacks, Qubic has still successfully mined 20% of the Monero blocks...

On August 6, Qubic's chief developer dkat pointed out on Discord: I asked for a quote yesterday, roughly $500 per IP, with a speed of 100Gbps, lasting 24 hours, including SYN Flood and reflection attacks. So it would cost about $20,000 a day for all Qubic nodes and the ecosystem. They have been DDoS attacking us for 7 consecutive days, so that's about $140,000...

What will happen to Monero in the future?

Based on various information, the Qubic network may indeed control more than 51% of the Monero hash rate.

This 51% attack, as stated by Qubic officials, is to validate technology and attract industry attention.

As promised by the Qubic official, Qubic will "start with a pure 51% dominance attempt, then shift to 'selfish mining' which only requires 33-40% of the computing power." The founder of Qubic also hinted that it will help Monero fight against the government in the future.

But how can the cryptocurrency community rebuild its trust in Monero?

Is Qubic an enemy or a new ally?

Worth continuing to observe.