Bitcoin Forum

 I've come across cases,where people claim that their blockchain was hacked and a huge amount was stolen from it, and I find it hard to belive it's possible because in my opinion it's impossible for a blockchain to be hacked because it's decentralized (not controlled by any authority) and it's managed by it's users, therefore for a hacker to penetrate into it, more than 50% of the nodes have to agree on that making it very difficult to penetrate, it's either they exposed their seed phrase or password.
 What's your opinion about this, also correct me if my opinion is wrong.

This solely depends on the protocol; being decentralized does not mean that when there is a means of hacking your system, you can't be hacked. There have already been several cases of different smart contract hacks ( Polygon  (https://www.google.com/amp/s/bitcoinist.com/hacker-exploits-vulnerability-on-polygon/amp/),  BSC  (https://www.google.com/amp/s/nairametrics.com/2022/10/10/explained-the-bnb-chain-hack/%3famp=1), and others) in which the hackers penetrated the system, minting some altcoins from nowhere and pushing them into the market.
 
Like I said earlier in a similar post, anything that is being programmed is hackable; any little mistake from the developers can be used against them. For now, Bitcoin is the online Blockchain that I have not come across or read anything about being hacked before. I believe this is as a result of the developers, who are working very hard to upgrade and fix any bugs discovered in the system that could lead to it being hacked.

It's their wallet that has been hacked, not the blockchain.
If your device is compromised or you use an unsafe wallet, it's possible that hackers can gain access to your private keys and steal all your fund.

Take note that any online device is always prone to hacking and for having complete security, you should use a trustworthy open-source wallet on an airgapped device or go for a hardware wallet.

Your opinion is partly wrong. In the past, blockchains have suffered the 51% attack despite people thinking that they are "decentralized"
The perfect example was the attack on XVG Blockchain ---> Privacy Coin Verge Succumbs to 51% Attack [Again] (https://www.ccn.com/privacy-coin-verge-succumbs-to-51-attack-again/)

Also search about attack on Ethereum Classic, BSV, Bitcoin Gold blockchains among many others

If we are talking about the decentralized project, it is extremely difficult and highly unlikely, for the blockchain to be hacked because one of the miner's duties is crypto transaction confirmation and also strengthening of the blockchain. Besides, blockchains are intended to be safe, open, and impermeable.

If you have time, I recommend reading Mastering Bitcoin^[1] or watching aantonop YouTube^[2] channels.
Both are good resources and you can learn the basics from them.

In short, there are no hacks in the blockchain because it is not a centralized system, but the system can be circumvented by double spending, which have a high chance of success for those who own the longest chain, meaning that you do not need to be 51% to start a double spending^[3] attack, but the longer you have the chain, the greater the chance of success and continuity This attack.


[1] https://github.com/bitcoinbook/bitcoinbook
[2] https://www.youtube.com/channel/UCJWCJCWOxBYSi5DhCieLOLQ
[3] https://youtu.be/ncPyMUfNyVM

You must know difference between network attacks like 51% attacks and hacks on the blockchain from its open source code. If the code from which the blockchain is built, is weak and exploited by hackers, big problems can occur.

I believe you are talking about 51% attacks, not back deeply into the blockchain code. With 51% attack, cost is high and you have small chance to maintain that high hashrate too long time. Miners, nodes when detect the issue will reconfig and switch their miners to other mining pools. Exchanges will quickly detect such attacks and halt all deposits and withdrawals so chance to succeed is not too big.

What can be affect is not the code used to build a blockchain, it is the blockchain itself that can be attacked which is called 51% attack. If the mining hashrate is not significant enough and 50% more, no attack. If it is more 50% than the rest of the miners, there would be 51% attack. In the past, some blockchains are attacked this way. This has been the only attack that I have known in which blockchain was hacked.

It's really not the blockchain that's been hacked, do not get confused OP, hacks happens through other means like crypto wallet breached cases or projects that provide LP get breached or bridges having a vulnerability.

There is this blockchain case that happened in my country, where this guy stolen over 140million in dollars, the news presenters stated that he hacked the blockchain and we later get to know that the guy work in the company and somehow find way to get his hands on the company's recovery seed, their main funds wallet.

People like confusing and mixing things up when it comes to hacks and blockchains.

Nope blockchain is secured only the smart contract, protocols, third party app, wallets, or anything build on top of a chain. This is possibly because there are vulnerabilities lies on those system which is normal since no platform is perfect to avoid such threat or breach, error and misalignment of codes. Thats a lot to take in OP but asking is always informative and helpful not only to you but to others who dont have ideas about this.

this is a very funny question honestly, if you think its not going to be possible why would they tell you try to keep your phrase key safe and private key as well this topic just need to be locked with due respect sir ;D ;D hacking  a blockchain is possible have seen or lets say if google search some past hacks you will get to see them.

I recently read a topic about the difference between token and Coin and the main factor that differ them is blockchain. Because Coin has its own blockchain while token depend on others blockchain. which indicates, that only those blockchain will be hack that are made on other blockchain. TO understand this you must have the knowledge of different types of Blockchain and limitations of them.

Because the Blockchain which is depending on other blockchain and could not exit independently. Such blockchain's developer are not giving any top level efforts to make them because such blockchains are made when the budget is low and you just have to launch a token which is new like a defi token maybe.

And yes, blockchain cannot be hack take an example of BTC blockchain but the the features of Blockchain can be tampered using smart contracts and other stuff like insertion of data.

If we don't remember the mistakes of developers yet, such as bad code writing, then the only known way of hacking is a 51 percent attack. But it is not possible, because you will have to capture fifty-one percent of the computers, and this is not possible. So bitcoin and ether cannot be hacked. They are time-tested.
If we go back to the bad code, I remember that there was news that the Polygon was hacked like that. As an example. An excellent blockchain that allowed us all to publish NFT for a meager payment. But it turned out to be vulnerable to hackers.

This answer is funny no offense. The Blockchain is not possible to hack but hacking the wallet is possible and that's why some people lose their crypto if they are not careful. Keeping the phrase or private key is not about the blockchain itself but what it used to connect to the blockchain so that you can do transactions. There are attacks to the blockchain like the 51% attack and 51% attack is not about private keys or seed phrase. You are giving wrong information mate.

It is feasible and has been done, however Blockchains are extremely difficult to hack in comparison to the traditional notion of hacking. To do so, one must control 51% of all nodes on the blockchain at the same time, which gets increasingly difficult as the number of nodes increases.

Consider this. in order to hack a bank, you must first gain access to the bank vault. This is difficult, but it is just one point of failure.

Imagine a vault scattered across 1000 sites, and to open it, you would need to hack 51% of them at the same time. Having said that, there are several sorts of blockchains and blockchain-based applications.

Banks can be robbed without going directly to the vault, because some of the money is kept in what you might call "hot drawers". In addition, the bank can be hacked in a way that you hack into their system and start emptying their clients' accounts - or you don't even have to do any of that, it is enough to collect information from bank cards and then with fake cards to withdraw cash at ATMs. When you take all this into account, it turns out that it is far easier to "hack" a bank, and very difficult to hack a serious system like Bitcoin blockchain.

Of course people are confused and ask questions like OP, but blockchain is a general term, and the fact that some blockchains have been hacked just means that some people and their projects were nowhere near the level of security that Bitcoin has.

They tell you to keep your seed phrase and your private keys safe because if it is found by anyone malicious, they will steal your assets, but if that happens it does not mean that the blockchain has been hacked, it is you the user that has been hacked and not the blockchain. If you use BTC, you should worry about your own personal security, because the Bitcoin blockchain is very secure.

OP, I learned that when hackers are working on any system they want to penetrate, they don't only work alone, but rather more than two hackers can agree on a decision to hack a system, and they will all be launching different attacks just to make sure they penetrate the system.

In the case of a private key or seed phrase, if you did not expose them to anyone, you could not be hacked. But if you mistakenly leak your security details, then you can be hacked.

Blockchain is the database, it is literary a chain of blocks. It is neither decentralized nor centralized on its own. The cryptocurrency project using the blockchain can use it in a centralized way or a decentralized way and neither of these affects the ability to hack it or not.
Of course when you say "hack" your definition is not clear, there are many different types of attacks. For example one of them is the 51% attack that was covered. Other attacks involve finding exploits in the protocol used in that cryptocurrency to do something you are not supposed to do like taking other people's money. This obviously depends on which cryptocurrency we are talking about. For example there has not been any such vulnerability in the Bitcoin protocol to allow people to do something like that, however altcoins are filled with such vulnerabilities. The most popular one is Ethereum that has a smart contract protocol that can easily be exploited like what happened with DAO and many others that came after it.

Most of the time, the hack that happens are always altcoins, it has been a long time since 2010 when Bitcoin was attacked, that wasn't really a hack, the attacker found a bug and exploited it to create about 184 billion BTC but was fixed by satoshi through a soft fork with new Bitcoin client at that time. If I recall very well, 2022 recorded the highest number of blockchain hacks in different altcoins, which was about 5 biggest apart from the exchanges that lost users money; the list below


https://nordvpn.com/blog/crypto-hack/

If you carefully examine these hacks, they are always insider work, when someone double-crosses the entire team and this is why I choose to like the Architecture of Bitcoin than all these funny coins that are created in the bull run to make money within the team and the early investors.

To be honest, the concepts underlying blockchain technology make hacking into a blockchain nearly impossible. Nonetheless, there are flaws outside of the blockchain that allow thieves to exploit. Hackers can steal blockchain by gaining access to cryptocurrency owners' Blockchain wallets and exchange accounts.

I have few cases I can use to demonstrate that hackers can gain access to blockchains in certain circumstances. This includes the scenarios listed below:

Inadequate security: Many blockchain breaches have occurred on exchanges, where users can trade cryptocurrency. Hackers will have easy access to data if the security practises surrounding the exchanges are lax.

51% Attack on Small-Scale Blockchains: For example, miners can create a forked version of the blockchain in which certain transactions are not reflected. This allows miners to build a completely separate set of transactions on the fork and claim it the true version of the blockchain, despite the fact that it is fake. This also allows the hackers to spend cryptocurrency twice. Because it is difficult for miners to obtain considerable control over larger and more complicated blockchains, 51% attacks are more likely on smaller scale blockchains.

Large scale Blockchain by creating errors: This could be increasingly common with larger, more complex blockchains. When this happens, hackers seeking for a way in can discover the flaws and launch an attack.  This has occurred with smart contracts, which function on a blockchain network. If there is a security hole in the blockchain network on which a smart contract functions, hackers may be able to steal money from users without being caught because the fraudulent conduct is not reflected.

Blockchains do not get hack, the wallets or contracts deployed on a blockchain get hacked just like Internet cannot be hacked, accounts on specific websites can be hacked. I hope you understand the basic difference. Most of them are insider job to runaway with user funds, this is why you have to stay away from projects which are promising giant returns or APY if you stake their tokens.

A contract is a smart contract like a software program which is deployed on blockchain and it's source code cannot be changed. Only the already deployed functions can be used to hack or empty the funds.

While not all blog chains are hacked, chances of your various software wallets or mobile wallets being hacked are high. Fraudsters are always waiting for this kind of opportunity where if you do a little mistake your wallet can get hacked for that mistake. In the case of various software wallets or mobile wallets, you should use extreme caution because when you deposit money in your software wallet or mobile wallets and when you use that wallet carelessly, the chances of your wallet being hacked will increase greatly, resulting in the loss of hard-earned moments, so you should always be extremely careful and do not share any personal information of your wallet with anyone.

t depends on the blockchain, and in our case it depends on how the cryptocurrency deals with the blockchain. Some cryptocurrencies are very centralized, but they deceive investors with the word blockchain, so they think that it is decentralized because of blockchain.

Here is an example, which is BSC, it contains 21 validators and they can stop the network, reverse transactions, freeze the coins inside the wallet or consider them invalid, here if these validators or Proof of Staked Authority (PoSA) are hacked, literally the blockchain has been hacked. USDT is another example where the company can freeze and withdraw funds as it wants. Here, if the company is hacked, the blockchain will be managed as the hackers want. Bitcoin is the unique model of the blockchain that has decentralized properties that have been tested and succeeded so far.