Questions tagged [attacks]

attempts by malicious users or software to subvert/manipulate the behaviour of an application or network

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What's stopping me from attacking the network by renting 51% of the stake for a few blocks?

The Ethereum market cap today is about $200bn. Theoretically, buying 51% of it would cost a stunning $100bn. Good luck getting that money hahah. However, I could ideally rent 51% of the staked eth for ...
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Why is it called a 51% attack if you need 2/3 of total stake in Proof of Stake?

Validation schemes require 2/3 of total stake to agree on the next block in proof of stake, so, if I'm a bad actor, outpacing honest validators requires 2/3 of total stake. Yet, attacks from malicious ...
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Proof 51% attack private ethereum - POW

I have a problem to simulate 51% attack in my private Etherum with pow validation. I have three nodes connected : Node 1 - Legit node Node 2 - Malicious Sender Node 3 - Malicious Miner In block 5 - I ...
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Understand this TX (attack on pancakeswap)

Can someone help me understand how this attack works? https://bscscan.com/tx/0x6781925966f5236c057d425e00378e4d4b8685c49eae9ddf48229ebcba682463 He basically SWAPS 0.000000001 BNB for some otkens, and ...
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When we say that a 51% control of total computation power could lead to a successful Sybil attack, do we refer to miners or nodes?

As per my understanding of the blockchain so far (Bitcoin and Ethereum) nodes and miners have different jobs to do in a blockchain network. Although the terms are extensively used interchangeably, ...
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How do these 2 functions differ in terms of security?

How are these 2 functions different in terms of security, there was a question on a forum and i don't understand function emergencyWithdraw(uint256 _pid) public { PoolInfo storage pool = poolInfo[...
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Security considerations: using events to trigger offchain actions

I need to trigger a sensitive offchain action based on a users interaction with my smart contract. My current approach is to emit and event (Trigger(msg.sender, 123)) and then use a filterQuery with ...
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can someone explain this line of the whitepaper?

To show how ethereum had made it's language turing-complete Vitalik in his white paper gave this example: "To show the motivation behind our solution(i.e using gas), consider the following ...
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How can I demonstrate attacks on Quorum-based smart contracts in my local test network?

Currently, I am conducting a research regarding the security and privacy vulnerabilities of Quorum-based smart contracts. However, so far I've been struggling to implement attack vectors in order to ...
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Flash loan price manipulation

I am quite new to flash loan and I don't fully understand it. I've been reading on flash loan attacks lately and notice often times it involves a huge dump on Uniswap to skew the price of a coin. I am ...
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8 votes
2 answers
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Commit-Reveal contract still vulnerable to front running. How can it be improved?

I'm writing a contract and I want to shield it from front-running as best as it can possible be done (obviously, fully preventing front running would be ideal). My implementation is very similar to ...
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How does the oracle judge whether the request has been attacked by a man in the middle

The oracle machine can initiate a request to the data source whose URL is the HTTP link address. How does the oracle machine determine whether the HTTP request has been attacked by a man-in-the-middle,...
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how do we use `commit/reveal` to count votes?

Let's say we are doing an election and it's easy to note that we need commit/reveal scheme to hide votes. So, we store hashes while users commit their votes. Now, let's say the election is over. How ...
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3 answers
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how does commit/reveal solve front-running?

I am trying to make sure I understand something correctly, so I will pose a problem with a solution. Problem: Let's say commit has been called. After this, we call the reveal. attacker listens to ...
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how can we stop front running for `approve` [duplicate]

function approve(address _spender, uint256 _value) returns (bool success) This is the ordinary ERC20 approval method. It's easy to figure out that we have a problem of front-running. Alice gives ...
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question about smart contract code possible vulnerability

I need help with one of my smart contracts. I wrote a smart contract that have functions that only emit events. The parameters of each event are some of the functions parameters. I want to ask if ...
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can we jam the ETH network with assert/require functions?

If we make for example a smart contract with a require function that is always false and we execute it tons of times (knowing that we will get our gas back cause of the revert function)will we be able ...
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Flash minting ether security considerations and attacks

Flash loans enable a class of attacks that have not been possible or observed as much in prior systems. Flash minting ether is a concept that is starting to be implemented. See Example of flash ...
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9 votes
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Flash loan security considerations and attacks

What do developers need to be aware of to make their contracts and systems safe against flash loans? What do they have to think about and protect against?
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Frontrunning Uniswap horror story transactions

From the Ethereum is a Dark Forest post, the rescue plan was: Deploy a Getter contract which, when called by its owner, would make the burn call ONLY if activated, and otherwise revert. Deploy a ...
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2 votes
1 answer
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Is the May 2017 contract creation attack still possible?

In May 2017, an "attacker" created a contract that attempts to create many other contracts(using many JUMPDEST operations in the creation bytecode) until it runs out of gas. I see the gas ...
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DaoAttack not working

I am trying to replicate the famous DAO attack for a cryptocurrencies course. I have the following contract already deployed on the blockchain. pragma solidity ^0.5.4; contract EDao { address ...
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Integrity of old blocks in the blockchain

I am learning Ethereum using Geth, and I am testing PoA-Clique networks. Now I have a conceptual doubt about old blocks integrity. Suppose I have a private blockchain network of only one miner node ...
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Transaction Timing Implications for Reentry Attacks

This is the classic reentry attack: function withdrawBalance() public { uint amountToWithdraw = userBalances[msg.sender]; (bool success, ) = msg.sender.call.value(amountToWithdraw)(""); ...
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Risk of Messages Not Having a Signature

As per my understanding transactions are signed before sending to Ethereum. Else, no transfer of Ether will happen. However, messages sent to Smart Contracts (SC) aren't signed (e.g., using methods....
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4 votes
1 answer
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What is the "pre-commit" scheme to defeat frontrunning attack?

I am writing to inquire feasible strategies to defeat Transaction Ordering Dependence (TOD) bugs. I learned from the best practice guideline such that we can use a so-called "pre-committed" scheme ...
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Griefing Attacks: Are they profitable for the attacker?

The following article explains one of the solutions for indirectly validate a block when cross-sharding transaction between two shards to prevent invalid blocks. The article called one of these ...
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adaptive vs. non-adaptive adversaries? Is there a precise, unique and general definition? (Updated)

In this Ethereum github page (Link to the page: https://github.com/ethereum/wiki/wiki/Sharding-FAQ#what-are-the-security-models-that-we-are-operating-under) there is a very brief definition of the ...
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Would a 51% attack be easier if an attacker can DoS certain nodes?

I am wondering whether a 51% attack would be simplified by being able to remotely crash miner nodes. Consider the following scenario: Malicious mining pool A controls 16% percent of the mining power ...
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3 votes
1 answer
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Understand the trending of newly-uploaded smart contracts that is considered as vulnerable

We tried to use Oyente to analyze some online contracts and drawed a diagram regarding the potentially vulnerable smart contracts ("reentrancy" bug) with respect to their creation time. So the y-...
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Create two contracts that each with different accounts.

I'm a newbie in blockchain. I am trying to repeat DAO attack using two different contracts, in my case DAO and Hacker. I want the 2 contracts belongs to 2 separated account, so I can see that the ...
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What is the work of self destruct in a contract?

How it can be used for handling force sending of ether to a contract without triggering fallback function ?
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A couple of questions on the Short Address attack

I have a few questions on the Short Address attack: Is it possible to apply this attack on a function which does not take encoded byte-code as input and execute it, for example - function func(bytes ...
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4 votes
1 answer
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Did DAO attacker gained ETH on Ethereum Classic?

I'm starting to study blockchain's world and the DAO attack caught my attention. I studied how it worked and the solution proposed by the Ethereum community. The hard fork splitted the blockchain in ...
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Denial attacks by submitting transactions with strategically calculated gas prices

As can be understood from the title, there is a specific form of denial attack where specific transactions are blocked by submitting transactions with strategically calculated gas prices. Example 1: ...
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1 answer
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How does the exploit in FOMO3D work?

With the recent release of the FOMO3D exploit in its smart contract, how does the exploit work?
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1 vote
1 answer
103 views

Account management risks of booting into Tails OS from USB using a "partially air-gapped" Linux PC

My threat tolerance is around a 3 out of 5 on the paranoia scale. What are the practical account management risks of using a flash drive loaded with Tails OS to boot into a Linux PC, which will only ...
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2 votes
3 answers
206 views

Are Ethereum Contracts Vulnerable to Hash Table Poisoning Attacks?

Does anybody know something about this? I know that in general terms we will say not, but looking on the internet I found that isn't sure the answer to the question: Can the EVM’s Internal ...
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1 answer
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Is it possible to use low mining complexity to remove some certain transaction in the past?

I have a question that has concerned me for a long time. It relates to the security and reliability of the blockchain applications. Let's assume I want to build an application that uses Ethereum or ...
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4 votes
1 answer
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ERC20 transfer - caller expects return but none provided - what happens?

If someone implements the ERC20 transfer() function without the return value as follows: function transfer(address to, uint256 value) public { require( ... usual checks ... ); balances_[msg....
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Who created this alt-Ropsten blockchain and why?

I usually test on Rinkeby, but this week I have to test some mining stuff, so I tried to get synced up with Ropsten. Unfortunately, after 3 days of trying, I still haven't had any success. The main ...
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1 vote
1 answer
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Best practices for a secure Ethereum private network? [closed]

What are the best practices for an Ethereum private network with n nodes (programmed with Geth), to be secure from possibles external attacks? I mean, which config parameters are recommended during ...
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1 vote
1 answer
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What is the Eclipse attack and how was it fixed in Ethereum?

In this paper the researchers describe the Eclipse attack https://eprint.iacr.org/2015/263.pdf. Can someone explain it briefly, what steps an attacker needs to take to perform the attack and how it ...
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6 votes
2 answers
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How does the 'secret chain' catch up with the real chain in the long range attack?

I'm trying to dig deep into Casper and one of the things that keep coming up is the long-range attack in PoS. I understand the attack at a high level - basically you would go back some large amount of ...
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5 votes
3 answers
2k views

Dealing with the short address attack

I'm writing a contract for an ERC20 token, based on Zepellin contracts. I noticed that their code doesn't handle the short address attack. Does it mean I shouldn't care about it?
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Why an attacker needs ~2^128 computing power to spoof membership of a key/value pair in a trie?

Ethereum Wiki: Every unique set of key/value pairs maps uniquely to a root hash, and it is not possible to spoof membership of a key/value pair in a trie (unless an attacker has ~2^128 ...
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Leverage short positions in decentralised PoW currencies

Hint I asked this question in a similar style already on bitcointalk and on bitcoin.stackexchange. But in these threads, there are no good answers and I thought maybe it would be better to ask the ...
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1 vote
1 answer
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Unable to replicate short-address attack

I was reading about the short address attack and decided to replicate and test the possible solutions. What I know about short address attack is if you skip n characters of your address, you end up ...
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What are the most common attack patterns on a Smart Contract? [duplicate]

i'm new to Solidity. After writing my first smart contract im fairly concerned about it's security, once deployed to the MainNet. What are the most important things i should check within my code? ...
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8 votes
2 answers
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Is sending some datas in the data field safe?

An airdrop ask to send it 0ETH with 150000 GAS and some datas in DATA field. Is it safe? What could be the aim of this transaction? Thanks.
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