Good day everyone,
I hope you are all having a good day, welcome to CryptoGod-1's blog on all things crypto. In this post I will be looking at the recent alleged 51% attack on Monero by the Layer-1 blockchain Qubic.
$75m Control Monero
The famed privacy coin Monero has seen a 51% hashrate seized by the Layer-1 blockchain Qubic according to claims from a 'X' post by user Pix. The post noted that the incident took place and saw Qubic take a level of control in which they could potentially rewrite the chain, double-spend transactions, or censor activity and proved the case of being “too big to attack” being wrong.
Qubic noted as part of a blog post earlier this week that the takeover was the result of a month-long campaign that culminated on Monday, coinciding with a six-block-deep chain reorganization that replaced 60 previously valid blocks. At the time the price of Monero fell around 7%. The 51% attack involves one party gaining control of the majority of a blockchain’s mining power or stake and then allows them to alter the chain’s history or block transactions.
The founder of Qubic, Sergey Ivancheglo, noted that they had a strategy to monopolize Monero’s mining and eventually reject blocks from rival pools. This came after they had incentivized CPU miners to direct their power toward XMR instead of other coins, promising better rewards through its network. Qubic note the event demonstrates it achieved full network control but Monero developers have pushed back.
The lead developer at SeraiDEX,, Luke Parker, noted that while the six-block reorganization took place it should not be considered a definite confirmation of a successful 51% attack, only that “an adversary with a high amount of hash got lucky.” Zhong Chenming, co-founder of cybersecurity firm SlowMist, feels differently as he stated that the attack “seems to have succeeded” and continued with a warning that Qubic’s pool could now be capable of rewriting the blockchain and censor any transaction.
As we all know in the blockchain space, transactions are verified by miners or stakers. In terms of the $5 billion privacy coin Monero, miners confirm transactions and the computational power used for mining is called the hashrate. Monero does have a built in mechanism to prevent large mining pools from behaving maliciously as it does not support dedicated mining machines (ASICs) and can instead only be mined using CPUs or GPUs. This is done to prevent all miners from gathering in one large mining pool and means in theory anybody can participate in mining with their own computer.
This method comes with a weakness, one which Qubic announced it would exploit all the way back in June. The company noted they would be redirecting their proof-of-work model, typically used for AI-related tasks, toward Monero mining. The XMR mined would in turn fund Qubic token buybacks and burns, creating a direct economic incentive to overpower the network. Qubic makes use of 'Useful Proof of Work' (UPow) which means miner's hash power is not only used to solve the mathematical problems for approving transactions (blocks) but also it is used to train the company's artificial intelligence system 'Aigarth.'
The reason for the attack? To show the power of the UPoW model. A large number of miners began to join Qubic back in May 2025 due to the successful use of its network hash rate for mining and rewarding users in the $QUBIC tokens. The Monero mined is sold for stablecoins which are then used to repurchase and burn $QUBIC tokens, creating a self-reinforcing economic loop. Qubic announced they would challenege Monero between August 2 and August 31 and it seems they reached their goal much sooner than anticipated.
The Monero community quickly mobilized and in late July members launched a distributed denial-of-service (DDoS) attack against Qubic’s mining pool. This briefly led to a drop in its hashrate from 2.6 gigahashes per second to 0.8 GH/s. This did not deter Qubic and by August they were able to compete the six-block reorg. A chain reorganisation is not uncommon in Monero as it can happen when two miners simultaneously mine blocks and the system choses one and discards the other. However this reorg was suspicious and it was Qubic testing the insertion of alternative blocks and potentially forking the blockchain. That alternative block was rejected, but it shows the power of what Qubic can achieve. Qubic even stated:
“In a move that has rewritten the rules of blockchain competition, a $300 million market cap AI protocol has successfully asserted its dominance over a $6 billion market cap privacy giant,”
For now, Qubic says it has “paused” the takeover, claiming it chose not to push the attack further. For how long remains to be seen. One of the more interesting points of note is the cost of this attack. It is estimated it cost Qubic $75 million per day according to calculations by Yu Xian, founder of the security company SlowMist. This is a figure which is impossible to recoup through mere speculative mining, especially given the daily block rewards of the entire Monero network are valued at approximately $150,000.
Qubic claimed to have reached 52.72% of the network hashrate, but to maintain this level they need to produce blocks equivalent to half or more of the entire network's output daily, which entails staggering costs for hardware, electricity, and operation. According to Crypto51, a website specifically designed to estimate the cost of executing 51% attacks on different PoW coin, the hourly cost to take control of the likes of Bitcoin would be around $2.7 million, while Litecoin: about $131,413 per hour. It does not show Monero, but the cost for even medium-sized PoW networks is staggering.
These seem like impossible figures until we look further into the overall benefit. If we consider that Monero's block time is about 2 minutes and the reward for each block is fixed at 0.6 XMR, then Qubic with a 51% control could earn about 432 XMR daily. The price for a single XMR is currently $246, meaning they could only profit about $106,000. Worthless, right?
Wrong!
Qubic distributes the Monero it mines in a 50%-50% ratio, as mentioned above, with half used for repurchasing and burning $QUBIC and the other half used for miner incentives. Miners are paid in $QUBIC, which has a market capitalization of less than $300 million, but is capable of producing Monero, with a market cap of nearly $4.6 billion. Therefore they could sell the mined XMR and destroy $53,000 worth of $QUBIC in a day, or $1.509 million worth of $QUBIC in a month! This will create the 'hash rate + token' combined economic model which Qubic desires.
Therefore miners will benefit from mining XMR but being rewarded in $QUBIC as the company artificially maintains the secondary market price of the token. When the price stabilizes or even rises they can exchange a relatively low token issuance cost for massive real hash rate support. This is luring miners to the blockchain. While Qubic is not relying on Monero's block rewards to make money, instead doing so for hype, it will certainly help to increase transaction volume and prices while attracting increased speculative buying. This is certainly one to watch if the price of $QUBIC maintains as miners will continue to flock. However, if it becomes difficult to maintain, it is likely that miners will return to more stable assets and a likely price collapse.
Have a great day.
Peace. CryptoGod-1.
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