Topic: [XMR] Monero - A secure, private, untraceable cryptocurrency - page 1481. (Read 4670972 times)

Is it OK to use latest wallet?  Do we have to update something?

But the fork, was that the purpose of the attack or accidental? Was he relying on the fact that it would be a while before anyone noticed?

Sounds to me as though mayhem was the intention.

So, I think figured out today how the attack worked.

Throughout the day, the chain was spammed with "mimic" pool payout transactions. This was to enlarge the median blocksize.

Then, when the block size hit the required size for the attack, the merkle tree hashing code was overflowed by including >511 tx (these were tiny tx with one input and no outputs) followed by two unique transactions with inputs and outputs. The last two transaction hashes in the tx merkle tree (512, 513) could be replaced with anything so long as they were valid tx hashes, as they didn't actually factor into the block hash. This was due to a bug in tree-hash.c. This was block 202612.

The net effect of this was that you could swap in any tx into the block at positions 512 and 513 so long as they were the same size and were valid.

Here's the interesting part: When the attacker mined 202612, he transmitted two different blocks to the network, both of which had valid block headers, and both of which contained different transactions in index 512 and 513.

Block 202612
Fork 1 (monerochain):

Fork 2 (chainradar, minergate):

Note that both of these above blocks have the same header hash, because the merkle tree code simply ignored including these tx into the tree. If it had, the block header hash would have been different.

So, now half the network had one block, and half had the other, but they both thought they were valid and exactly the same even though they weren't.

Now, here's how the attacker forked the network. Two blocks later, at height 202614, the attacker generated and submitted two new blocks. These blocks contained the transactions below:

Block 202614
Fork 1 (monerochain):

Fork 2 (chainradar, minergate):

Noticed that these two new blocks both contain tx which the other chain already had -- at this point the network forked, because for each network one of these blocks would be invalid because it contained a doublespend of transactions that were already included.

Here's some output from a daemon on the forked network (fork 1, monerochain), from exactly when it hit the fork point:

This has been the most elaborate attack on a cryptocurrency I've ever seen -- it required incredible coordination and took great lengths to hide itself from being see from casual users of the network until it was too late. Of course, we were watching and could tell something was up, so we caught the fork immediately and were able to protect our users by notifying them and the exchanges of it. Still, I'm frankly amazed at the lengths the attackers went to to conduct this attack, and the complexity of it.

I cannot create an account.
The website is stuck at:
https://poloniex.com/signup_validate.php

Am I under personal attack or something?

Kudos to all those who were involved in the quick investigation&fix, core team of course but also the few programmers revolving around. Thank you guys, really!

Kudos to the whole XMR community for the way it reacted, especially considering the amount of trolling against us. In cryptoland, we look like one of the few wise grown-up adults communities in a world of stupid children.

I find it extremely funny to think that the suckers behind the attack were trying to obtain a financial gain from it, and at this point it seems to be a *complete* fail.

Seems polo is trading, huge volumes over last hour back to the low mid 400s after taking a dive.

Wonder why Bittrex is still down?

O well, been working all day and didn't worry once as a holder of XMR here. I did expect to lose more liq. value though, the market looks really strong. I'm not thinking about the short term either way with XMR but I'd be lying to say I'm not happy to see the market response on polo after trading resumed.

Great job monero dev(s) with the way you handled this

XMR deposit is disabled 因技术维护，虚拟币充值暂停，感谢您谅解和支持。

translated:
XMR deposit is disabled due to technical maintenance, the virtual currency recharge pause, thank you for your understanding and support.

I'm trying to withdraw 2 digits of XMR.

I downloaded the Windows x64 blockchain yesterday and have synced up to 202656. Stuck there for hours now so I must be on the wrong chain.

I downloaded it again this evening, but the file size suggests to me it's the same as yesterdays and I don't want to end up in the same position again.

Could the OP be updated with the correct Windows blockchain ASAP please! Ta

Poloniex. I never hold funds on exchanges.

Poloniex has worked great for me.

how come it doesnt work? i think bter make you pay a 1% fee on withdrawal so that may be the reason why you cant withdraw? maybe you're withdrawing too much? otherwise, whats the error msg?

for hit and runs, i recommend mintpal and bter, but you can only hit small as the volume is very low there. most volume happens on poloniex and hitbtc

Can someone advise me on a place where I can do a hit and run which actually works? I don't want to have them locked up somewhere online.

edit: never did a personal transaction through this forum but I think I might want to try this as well, or shouldn't I?

Too late, I just deposit some satoshis, did a market buy monero and went for withdrawal, basically a hit and run.

The impression came when everything else already happened.

(1) Don't buy XMR on BTER, and (2) if it made a great first impression, then you would not be buying them this cheap

Cheers!

Well, I also just made my first purchase, but they are locked on BTER because I can't withdraw.
Very good first impression!

This kind of post is such good news.  Today made the coin, and community, incalculably stronger :-)

Why can't I withdraw monero from BTER? Anyone else got this problem?

Just made my first ever XMR purchase - 5 minutes of XMR dev time for attack mitigation and security.

Thanks, devs!!

Doubtful it would work in this case, my TOR sense is tingling.

Those IP addresses are all there...  The mods can see them.  Of course there's tor.