38 votes
Accepted

What exactly is the Nothing-At-Stake problem?

You don't lose anything from behaving badly, you lose nothing by signing each and every fork, your incentive is to sign everywhere because it doesn't cost you anything. So as it doesn't cost you ...
euri10's user avatar
  • 4,640
35 votes

Why is my node synchronization stuck/extremely slow at block 2,306,843?

Update Mar 5 2017 The state cleaning was announced by Vitalik Buterin in the tweet State clearing 100% complete dated 23:07 Nov 29 2016. This time corresponds to block 2,718,436. The Clearing ...
BokkyPooBah's user avatar
  • 40.3k
23 votes
Accepted

Ropsten testnet is under kind of attack? What can we do?

Update - 25th March 2017 Ropsten has been revived! We are pleased to announce that the Ropsten testnet has been revived! Thanks to a generous donation of GPU hashpower, the Ropsten chain has ...
Richard Horrocks's user avatar
20 votes

What exactly is the Nothing-At-Stake problem?

tl;dr from Casper 101 [In proof of stake] if there’s a fork in the chain, the optimal strategy for any validator is to validate on every chain, so that the validator gets their reward regardless of ...
jonchoi's user avatar
  • 376
13 votes
Accepted

Can you attack/ddos/spam a single contract?

There's no concept of DDOS in contracts in the same vein as a web server in Ethereum. You can send as many transactions as you want, but you won't be able to block access to it, simply by flooding it ...
Simon de la Rouviere's user avatar
12 votes

TheDAO hack FAQ: How did the attack happen on 17 June 2016?

What happened? 3,641,694 ETH where splitted out of theDAO. The attacker found a loophole in the regular splitDAO function so that they could reuse the same DAO tokens over and over again. How ...
12 votes

Is sending some datas in the data field safe?

Generally, no! It can be dangerous. If you are asked to send such a transaction, you should understand what is the source code of the address you are sending to, and what function you might be ...
eth's user avatar
  • 85.7k
11 votes
Accepted

How many The DAO recursive call vulnerability attacks have occurred to date?

Summary As of 22/06/2016 AEST, 5+ attacks are identified below: # 1 The major 17 June 2016 attack #1 that pictured in ether.camp/dao-thief (info from user iamtrillion in the post DAOhub.org - [...
BokkyPooBah's user avatar
  • 40.3k
10 votes
Accepted

What is the Long-Range-Attack in Proof-of-Stake?

In a naively implemented proof of stake, suppose that there is an attacker with 1% of all coins at or shortly after the genesis block. That attacker then starts their own chain, and starts mining it. ...
Gruff McGruff's user avatar
9 votes
Accepted

How many ethers have been drained through the recursive call attacks on The DAO?

Summary Here are the statistics, based on the drains that I have identified in How many The DAO recursive call vulnerability attacks have occurred to date?: Type # Balance ExtraBalance ...
BokkyPooBah's user avatar
  • 40.3k
8 votes
Accepted

What are the balances of The DAO and it's child DAOs on the Ethereum Classic chain?

I'm using the same unmodified script from How many ethers have been drained through the recursive call attacks on The DAO? to calculate the balance of The DAO and it's child DAOs. For a finer ...
BokkyPooBah's user avatar
  • 40.3k
8 votes

Why is my node synchronization stuck/extremely slow at block 2,306,843?

On a practical note, just remove your blockchain and synchronize again. The blockchain bloat has been removed already. Stop your node and/or close your Ethereum wallet. Remove the chaindata. for ...
q9f's user avatar
  • 32.9k
8 votes

Flash loan security considerations and attacks

As we work on flash loan attack debriefs, we can gather a lot of information about what could have been taken as preventative measures. It's important to understand how these flash loans work before ...
Patrick Collins's user avatar
7 votes
Accepted

Why were empty accounts allowed to be on the blockchain?

What were the technical challenges why the protocol didn't prevent them in the first place? There weren't any particular technical challenges. It was simply an oversight, "a mistake, a flaw in the ...
cdetrio's user avatar
  • 386
7 votes
Accepted

Is it Safe to Share the Wallet Keystore File Without Password?

You should definitely not give away your keystore file as it contains your encrypted private key. The only thing that can decrypt your private key is your password. However, one could perform a brute ...
Zenos Pavlakou's user avatar
6 votes

Why are coins at risk when honestly staking?

In the current vision of Casper Proof of Stake protocol, the validators (who are staking), when eligible, need to bet on the finality of blocks. More technically speaking, each bet has to specify for ...
Alexey Akhunov's user avatar
6 votes

TheDAO hack FAQ: How did the attack happen on 17 June 2016?

A very highlevel, very simplified answer. If you send a split request to the DAO, it checks your token account, creates a new copy of the DAO with your ethers in it and then reduces your account by ...
6 votes

What is a Sybil attack?

A Sybil attack occurs when one actor acts as multiple separate entities. Because many distributed systems have no form of identity management beyond accounts, and because accounts are trivially ...
Nick Johnson's user avatar
  • 8,154
6 votes
Accepted

Is it possible to attack "the DAO" attackers new splitted DAO?

That idea may have been part the motivation behind this post: "Is anyone in the process of splitting from the DAO right now? It would really help if the person whose split will finish in 2 hours (#69)...
user36182's user avatar
  • 268
6 votes
Accepted

When will the Baddies have access to the hacked funds on the Ethereum Classic chain?

The Baddies joined into the Split Proposal #59 where they were not the curator. From this split, the Baddies created a number of split proposals where the Split Proposal #59.10 was used to split out ...
BokkyPooBah's user avatar
  • 40.3k
6 votes
Accepted

How was the state-bloat attack that led to the EIP 150 hardfork performed?

Ancient history, but here goes :-) There was one coordinating contract for the initial attack. A later version had a more complex algorithm to generate the empty account addresses, presumably to try ...
benjaminion's user avatar
  • 9,267
5 votes

How was the recursion created that lead to theDAO hack?

This is the problematic line of code in the withdrawRewardFor function: if (!rewardAccount.payOut(_account, reward)) <-- reentrant exploit throw; paidOut[_account] += reward; The ...
Ismael's user avatar
  • 30.6k
5 votes

What is a Sybil attack?

Sybil is a 1973 book by Flora Rheta Schreiber about a woman with sixteen different personalities that has been made into a mini-series. From Sybil attack - Wikipedia: The Sybil attack in computer ...
BokkyPooBah's user avatar
  • 40.3k
5 votes

What is a replay attack?

To avoid replay attack use EIP155 transaction types which are available since block 2675000. They incorporate chainID to the transaction signature. Make sure your wallet software is EIP155 enabled and ...
Nulik's user avatar
  • 4,061
5 votes
Accepted

What was the second vulnerability used in The DAO attack on 17 June 2016?

It's not so much a vulnerability, but the attack cleverly transferred its DAO tokens between 2 accounts, by using function transfer(address _to, uint256 _amount). So the fallback function of the ...
eth's user avatar
  • 85.7k
5 votes

Besides TheDAO - what are some examples of where Ether has been hacked, stolen or lost?

After the DAO hack, some people created a list together on Reddit. You can also check Vitalik's blog post about it: The DAO (obviously) The “payout index without the underscore” ponzi (“FirePonzi”) ...
5 votes

Ropsten testnet is under kind of attack? What can we do?

Ropsten is to be considered dead, and parity launched a Proof of Authority testnet called Kovan. Read the proposal here: https://github.com/kovan-testnet/proposal To update your testnet from ropsten ...
q9f's user avatar
  • 32.9k
5 votes

How does the 'secret chain' catch up with the real chain in the long range attack?

As the author of the quoted article noted himself: Originally, I thought that this problem was fundamental, but in reality it’s an issue that can be worked around. One solution, for example, is ...
medvedev1088's user avatar
5 votes

How did I get my private key stolen?

The attacker used the transfer() function to transfer the USDC, which means it came from your private key. If you didn't sign any suspicious messages then that means the attacker has your private key. ...
Peter's user avatar
  • 166
4 votes

Can you attack/ddos/spam a single contract?

Contracts can't be DDOS, because doing so means attacking the entire peer-to-peer network, since every node makes the contract available. The possibility of an "attack" on a contract depends on the ...
eth's user avatar
  • 85.7k

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