A 51% attack is a type of attack against blockchain that occurs when a miner (a single attacker) or group of miners gain control of more than 50% of the network’s total mining/hashing power, allowing them to manipulate the blockchain and double-spend coins. This type of attack is particularly dangerous because it allows the attacker to reverse transactions and prevent new transactions from being confirmed.

Ethereum Classic blockchain

One of the major incidents of a 51% attack occurred in January 2019 on the Ethereum Classic blockchain. An unknown attacker was able to control more than 50% of the network’s mining power and used it to double-spend coins, reversing transactions and stealing more than $1 million worth of cryptocurrency.

Additionally, in August 2021, the Ethereum Classic blockchain was hit by another 51% attack incident where the attacker used their control over the network to double spend $5.6 million worth of cryptocurrency.

Bitcoin Gold blockchain

Bitcoin Gold, a cryptocurrency that forked from the original Bitcoin blockchain in 2017, experienced a 51% attack. This resulted in the double-spending of over $72,000 worth of Bitcoin Gold tokens. This was the second time that Bitcoin Gold has suffered such an attack, with $18 million worth of tokens being stolen in May 2018.

Bitcoin SV blockchain

In the case of Bitcoin SV (BSV), there have been several instances of 51% attacks reported in August 2021.

But according to the Bitcoin Association, the hacker’s attempts to perform a 51% attack were not successful.

Other major incidents

In addition to these incidents, there have been several other instances of 51% attacks on other smaller blockchain networks such as ZenCash, Monacoin, and Verge. For example, in April 2018, the ZenCash blockchain fell victim to a 51% attack, resulting in the attacker stealing more than $500,000 worth of cryptocurrency. Similarly, in May 2018, the Monacoin blockchain was targeted in a 51% attack, resulting in the attacker stealing more than $90,000 worth of cryptocurrency.

How to fight 51% attacks

These attacks also highlights the importance of implementing security measures such as checkpointing, which allows the network to periodically take a snapshot of the blockchain and use it as a reference point to detect and prevent any malicious activity.

Another way of mitigating such type of attack is to use a different consensus mechanism which is more resistant to 51% attack like Proof of Stake (PoS) which do not rely on hashing power to secure the network.

Conclusion

The 51% attack is a serious threat to the security of blockchain networks, particularly smaller networks. It is crucial for blockchain networks to take steps to prevent such attacks and for users to be aware of the risks associated with small and under-secured blockchain networks.

Bitcoin, the world’s first and most widely recognized cryptocurrency, has revolutionized the way we think about and use money. It has also, unfortunately, opened the door to a new type of crime: Bitcoin hacking, fraud and scams.

If you own bitcoin, or are thinking about buying some, it’s important to be aware of the various scams and frauds that can target you. Here are some tips to help you protect yourself:

Don’t fall for phishing attacks:

Scammers will often send fake emails or texts claiming to be from a legitimate bitcoin exchange or wallet service, asking you to click on a link and enter your login details. Don’t fall for it! If you receive an unsolicited message that seems suspicious, do not click on any links or enter your login information. Instead, go directly to the website of the exchange or wallet service in question and log in from there.

Use a reputable exchange:

If you’re buying bitcoin, be sure to use a reputable exchange. Look for an exchange that has a good reputation, a long track record, and a user-friendly interface. Avoid any exchange that seems shady or unprofessional.

Avoid Telegram scams:

Unfortunately, Telegram is full of fake initial coin offering, scam projects, Ponzi schemes, fake subscriptions to paid dump & dump groups ..etc. it is important to be cautious when interacting with unknown individuals or groups on the platform. Do not click on links or enter your personal information unless you are certain that the request is legitimate.

Be aware of exit scams:

Do not store your cryptocurrency in online crypto exchanges. Online Exchanges are not safe for storing cryptocurrencies. If you keep your private keys in a safe place, your coins can’t be stolen when an exchange is compromised. We have covered some exit scams before like: ADAX, Claymore and NovaChain. And always remember, Not Your Keys, Not Your Coins. It’s that simple.

Use a hardware wallet:

A hardware wallet is a special type of device that stores your bitcoin offline, making it much harder for hackers to steal your funds. If you own a significant amount of bitcoin, it’s a good idea to invest in a hardware wallet to keep your funds safe.

Don’t share your private keys:

Your private keys are like the passwords to your bitcoin and your cryptocurrency wallets. Keep them secret and secure, and never share them with anyone.

Be cautious of “free” bitcoin offers: If something seems too good to be true, it probably is. Be wary of any offer that claims to give you free bitcoin. These types of offers are often scams designed to steal your personal information or trick you into investing in a fake cryptocurrency.

Don’t fall for Bitcoin investment schemes:

These scams involve individuals being duped into investing in fake or fraudulent investment opportunities, resulting in the loss of their money. Always be cautious of “too good to be true” offers.

Avoid Rug pull scams:

Rug pull scams are a type of cryptocurrency scam in which a group creates a fake cryptocurrency and promotes it as a promising investment opportunity. The group will often use social media, Telegram, or other online platforms to promote the coin and get people to invest in it. Once the group has raised a significant amount of money, they will “pull the rug” out from under the investment by disappearing and leaving the investors with worthless coins. This type of scam is called a rug pull because it is similar to the action of pulling a rug out from under someone, causing them to fall. Rug pull scams are particularly insidious because they can be difficult to detect, and people who fall victim to them may lose significant amounts of money. It is important to be cautious when considering investments in cryptocurrencies and to thoroughly research any coin or project before investing.

Enable two-factor authentication:

Two-factor authentication (2FA) is an extra layer of security that requires you to enter a code sent to your phone or email in addition to your password when logging into your account. This helps to prevent unauthorized access to your account even if someone else gets hold of your password.

Use strong and unique passwords:

Make sure to use strong, unique passwords for all of your accounts, and avoid using the same password for multiple accounts. It would be a good idea to use a password manager that can help you generate and store strong, unique passwords for all of your accounts.

Enable transaction notifications:

Some exchanges and wallets offer the option to receive notifications for all transactions. This can help you stay on top of your account activity and be aware of any unauthorized transactions.

Use a reputable antivirus software:

Installing antivirus software can help protect your computer from viruses and other malware that could compromise your bitcoin wallet or steal your personal information.

Enable account recovery options:

Many exchanges and wallets offer account recovery options, such as the ability to reset your password or access your account through a secondary email address. Enabling these options can help you regain access to your account in the event that you lose your login credentials.

Use a multi-sig wallet:

A multi-sig wallet requires multiple signatures, or approvals, before a transaction can be made. This can help protect your bitcoin from being stolen in the event that one of your signatures is compromised.

And finally, use a virtual private network (VPN):

A VPN can help protect your online activity and keep your connection secure when using the internet. This can be especially important when accessing your bitcoin wallet or making transactions.

By following these tips, you can protect yourself from bitcoin fraud and scams. Remember to always be vigilant, and never share your personal information or login details with anyone.

Bitcoin core developer Luke Dashjr has lost 200 BTC in a hack attack. He reported on Twitter that one of his hot wallets was hacked and around 216 BTC were transferred to this BTC address 1YAR6opJCfDjBNdn5bV8b5Mcu84tv92fa. The value of the stolen bitcoin at the time of the hack was approximately $4 million.

The hack serves as a reminder of the risks involved in holding and using cryptocurrency. While Bitcoin and other cryptocurrencies have gained popularity in recent years due to their decentralized nature and the potential for high returns on investment, they are not immune to theft and fraud. It is important for individuals and organizations holding cryptocurrency to take steps to secure their assets, such as using strong passwords and enabling two-factor authentication.

The hack also highlights the importance of keeping software up to date. Bitcoin Core is the reference implementation of the bitcoin network and is maintained by a team of volunteers. These volunteers work to fix vulnerabilities and improve the security of the software. It is important for users of Bitcoin Core and other cryptocurrency software to stay current with updates to ensure that they are protected from known vulnerabilities.

In the wake of the hack, the developer has urged other Bitcoin users to be vigilant and to take steps to protect their assets. He has also called on the community to work together to improve the security of the cryptocurrency ecosystem.