In crypto, few events shake a network to its core like a 51% attack. The recent headline-grabber? A $300M blockchain called Qubic taking control of over half the mining power of Monero, a $6B privacy-focused cryptocurrency renowned for its untraceable transactions.
And no—this wasn’t a rivalry between privacy coins. This was an experiment in Useful Proof of Work (uPoW) and a demonstration of computational might.
What Is a 51% Attack?
If a single entity controls more than half of a blockchain’s total mining power, they gain the ability to:
- Reorganize blocks
- Censor transactions
- Double-spend coins
It’s a theoretical vulnerability that most major PoW networks hope never to face. But Monero just did.
How Qubic Pulled It Off
Instead of solving meaningless hash puzzles like Bitcoin or Monero’s native miners, Qubic’s uPoW uses computational power to train AI models.
In May, Qubic began mining Monero—not for dominance, but to showcase that their mining layer could both:
- Support Monero’s network
- Generate value through XMR rewards
Here’s the loop:
- Qubic miners mine Monero and Tari.
- Rewards are converted to USDT.
- USDT is used to buy Qubic tokens on the open market.
- Those tokens are burned, reducing supply.
The result? Monero mining via Qubic became more profitable than standalone Monero mining—fueling rapid growth from 0% to 10% to over 50% of Monero’s hash rate in just weeks.
The Climb to 51%
From 21%… to 45%… to 50%… until finally, the number broke the critical 51% threshold.
Monero’s defense? Attempts to disconnect Qubic miners via DDoS failed. According to Qubic’s founder Sergey Ivancheglo (CFB), the goal was to test whether Monero could defend against a majority takeover. The answer: not this time.
Interestingly, the push to hold dominance came largely from the Qubic community itself—driven by what’s become known as the “Qubic Army.”
The Cost of Control
Maintaining 51% dominance isn’t cheap. Estimates place the cost at $75M per day. Ivancheglo made his plan clear: once control was secured, Qubic would enter stealth mode, hiding hashrate data and distributing it across multiple addresses.
With majority control, Qubic could:
- Reject transactions from other miners
- Favor its own transaction sets
- Influence block propagation
But the team publicly decided not to take over Monero’s consensus rules—sparing the network from deeper disruption.
Why It Matters
51% attacks are rare, but history shows they’re not impossible. Bitcoin Gold (2018, 2020), Ethereum Classic (2020), and Verge (2018) have all been hit.
The Monero case is a wake-up call: even well-established blockchains can be overtaken if conditions align. And while executing a similar move on Bitcoin would be exponentially harder and costlier, the underlying vulnerability exists.
The Bigger Picture
For Qubic, this was more than a stunt. It was a proof-of-concept for uPoW’s flexibility and raw power—demonstrating that a network designed to train AI could, if directed, dominate one of crypto’s most private chains.
The Monero network continues, its core features intact. But the experiment leaves a lingering message for all PoW projects:
Decentralization isn’t a given—it’s a moving target.
⛓️ #QubicMagazine $Qubic
