The Emerging Narrative
Something unprecedented is unfolding across the cryptocurrency landscape in June 2018. At least five blockchain networks — monacoin, bitcoin gold, zencash, verge, and litecoin cash — have fallen victim to 51% attacks in the span of just one month. These aren’t theoretical vulnerabilities discussed in whitepapers anymore. Attackers are actively hijacking networks, rewriting transaction histories, and walking away with millions of dollars in stolen cryptocurrency, targeting exchanges as their primary cash-out mechanism.
Bitcoin traded at $7,624 on June 8, 2018, barely moving in what MarketWatch described as the tightest weekly trading range of the year — just 5.3% from bottom to top, stuck between $7,300 and $7,800. Ethereum sat at $601, also relatively flat. The calm in major markets, however, masked a brewing storm in the altcoin space, where smaller networks with limited hash power were proving dangerously vulnerable to well-coordinated attacks.
Catalyst Identification
The catalyst behind this sudden spike in 51% attacks is deceptively simple: economics. NYU computer science researcher Joseph Bonneau published research in 2017 estimating how much it would cost to execute these attacks by renting computing power rather than purchasing expensive mining equipment outright. His conclusion was stark — the cost was far lower than most people assumed, and attacks were likely to increase.
Bonneau himself expressed surprise at how quickly his prediction materialized. “Generally, the community thought this was a distant threat,” he told CoinDesk. “I thought it was much less distant and have been trying to warn of the risk. Even I didn’t think it would start happening this soon.”
The attacks follow a consistent playbook. Bad actors amass more than half of a network’s total hashing power — something feasible on smaller chains with modest security budgets — and then exploit that majority control to execute double-spend attacks against exchanges. The bitcoin gold attacker successfully double-spent two large transactions sent to an exchange. The zencash attacker pulled off three separate attacks, making off with more than 21,000 ZEN tokens worth over $500,000 at the time.
Key Players to Watch
The victims tell a revealing story about where the risk concentrates. Bitcoin gold, a Bitcoin fork with a market capitalization still in the hundreds of millions, was compromised despite its relatively high profile. Zencash, a privacy-focused fork of Zcash, was hit multiple times, suggesting attackers found a repeatable exploit. Even verge, which had already suffered a previous attack exploiting insecure code in its protocol, was targeted again through its lower protocol layer.
EOS, meanwhile, sat at position number five on CoinMarketCap with a price of $14.04 and a market cap of $12.58 billion, fresh off its record-breaking $4 billion ICO that raised 7.12 million ETH. The contrast was stark — while well-funded projects like EOS were launching mainnets and building infrastructure, smaller altcoins were struggling to maintain basic network security.
Litecoin, ranked sixth with a price of $120 and a $6.8 billion market cap, and Cardano at $0.205 with a $5.3 billion market cap, were large enough to resist such attacks. But the long tail of altcoins below the top 20 — many with market caps under $1 billion — faced existential questions about their security models.
Risk Assessment
The implications extend far beyond the immediate financial losses. Every successful 51% attack undermines confidence in the fundamental security premise of proof-of-work cryptocurrencies. If a network can be compromised by anyone willing to rent sufficient hashing power for a few hours, the entire “trustless” value proposition comes into question.
Exchanges bear the brunt of these attacks, since they’re the targets where double-spent tokens get converted into other cryptocurrencies. This creates a secondary risk: exchanges may delist vulnerable coins entirely, destroying liquidity and effectively killing projects. Several exchanges had already begun requiring dramatically higher confirmation counts for deposits from smaller PoW chains, slowing transactions and degrading user experience.
The cost factor is particularly alarming. Bonneau’s research demonstrated that renting hash power through services like NiceHash could make attacks economically viable even on networks that previously seemed secure. As hash power rental markets mature and become more liquid, the barrier to launching a 51% attack continues to drop.
Strategic Conclusion
For investors and participants in the altcoin market, the message is clear: hash power matters more than hype. A cryptocurrency’s security budget — the total economic cost required to attack its network — should be a primary consideration in any investment thesis. Projects with low hash rates, regardless of their technological promises or community enthusiasm, carry a fundamental vulnerability that no amount of marketing can fix.
The wave of 51% attacks in June 2018 may represent a necessary maturation event for the cryptocurrency space. Just as exchanges learned hard security lessons from the Mt. Gox era, proof-of-work networks are now confronting the reality that economic incentives cut both ways. The networks that survive will be those that can attract sufficient mining interest to make attacks prohibitively expensive — or those that adopt fundamentally different consensus mechanisms altogether.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Cryptocurrency investments carry significant risk, including the potential for total loss. Always conduct your own research before making investment decisions.
five networks in one month. monacoin, bitcoin gold, zencash, verge, litecoin cash. if your chain has low hashrate you are just waiting to get robbed
verge got hit THREE times that year and still kept going. some chains just refuse to die lol
verge getting hit three times and surviving tells you everything about the sunk cost fallacy in crypto communities
Bonneau nailed the economics. renting hashpower from NiceHash to attack a small chain costs pennies compared to what you can double-spend
renting hashpower from nicehash to attack small chains was absurdly cheap. bonneau calculated it at a few thousand dollars for millions in double spend potential
nicehash became the weapon and the victim at the same time. they got hacked for millions but also enabled most of these attacks
bugzapper nicehash was basically a rental service for 51% attacks and nobody wanted to admit it. cheap hashpower plus vulnerable chains equals inevitable disaster
the economics are even worse now with cloud mining. any small chain running equihash or scrypt is basically a sitting duck
Bonneau calculating attack costs in the thousands against double spend potential in the millions is still the most important crypto security paper ever written
verge got hit three times and just kept going. the definition of sunk cost fallacy in crypto communities
verge getting hit 3 times is wild. most projects would have one attack and die. the sunk cost community kept rebranding the same broken chain for years
bonneau calculated the attack cost at a few thousand dollars against millions in double spend potential and exchanges still did nothing. the entire 2018 altcoin security model was a house of cards
BTG got hit and still exists somehow. the fact that recovery was even possible tells you how low the stakes were for attackers back then
five networks in one month and the only takeaway was small chains need to change consensus or accept the risk. most chose to accept it
double_spend_ five networks in a month and the only fix was ‘switch to a different consensus mechanism.’ the whole security model for small chains was broken by design
BTG got 51% attacked and Bittrex still listed it for years after. exchanges cared about volume not security back then
nicehash literally built a marketplace for renting hashpower and then acted shocked when people used it to attack chains. the business model was the vulnerability
reza k nicehash being a rental marketplace for attacks is the most on-brand crypto thing ever. build the weapon and sell it to both sides
Reza K. nicehash built the gun and sold it to whoever paid. the fact that nobody went to jail for enabling those attacks is wild
verge getting hit 3 times and the community keeping it alive is the most sunk cost thing in crypto history. at some point you just let go
five 51pct attacks in one month and exchanges kept listing these coins. the due diligence was basically zero in 2018
Bence F. BTG got hit and Bittrex kept it listed for years after. exchanges did not care as long as volume was there
Karan S. bittrex kept BTG listed for years after the attack because delisting meant losing the trading fees. exchanges in 2018 were parasites feeding on volume regardless of security risk
Karan S. BTG getting 51pct attacked and Bittrex keeping it listed tells you everything about exchange risk management in 2018. volume trumped security every time
Nicehash literally built a hashpower rental marketplace and acted surprised when people used it to attack chains. the tool was the vulnerability
reorg_void_ NiceHash built a hashpower marketplace and nobody considered that renting hashpower by the hour is literally a 51pct attack toolkit. the business model was the exploit
verge getting hit three separate times and still trading is the most sunk cost behavior in crypto. at some point the community should just accept the chain is broken