Quote from: lontivero on December 19, 2014, 03:44:06 PM

Quote from: johoe on December 19, 2014, 02:04:30 PM

105.9 BTC stolen by 1M77fUCzQrmY8jHRRgpzDVPAK5eQ31bwxZ

They were sent to this address at approximatly 00:50:20 GMT 1M77fUCzQrmY8jHRRgpzDVPAK5eQ31bwxZ
Within 17 seconds of me depositing 100 btc into my account they were stolen and transfered to another address without me even being logged into the blockchain wallet servce.

I robot that scans new transactions (timestamped or not), awsome!

I doubt it was a bot for three reasons. (1) This was one hour after the problem started. Nobody would set up a bot for this so fast, you have to understand the problem first. (2) the money was stolen in two transactions, first 99 BTC, then 0.9889 in a second transaction. A bot would have taken everything in one. (3) why didn't he set up a bot for all the other weak addresses?

My guess is that someone created a new address and found 5.9 BTC. He transferred that to his other address. When this worked, he looked for more and created new addresses, maybe also new accounts. He was still online when the 99.989 BTC arrived and got a notification. 17 seconds should be enough to open the send tab, enter 99 BTC, fill in the address (it was probably in his autofill history), and click send. It was a lot of luck, though.

Quote from: Supercomputing on December 19, 2014, 07:20:33 PM

Sorry mate, this bug was trivial to exploit by others. It took me less than 30 minutes after reading this thread to reproduce the bug.

It took him about an hour from the first weak transaction to the exploit. And there was no information on the net at that time.
I think this was not directed, see reason (3) above, but pure unbelievable luck. (It is not luck that he created the same address as someone else - that would have happened often enough that night - but it is luck that someone put the unbelievable sum of 99.989 BTC on just this address).

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Blockchain.info has no valid excuses if some of the BTCs were stolen by dishonest people and should be held accountable. Use Blockchain.info at your own risk.

Blockchain.info promised to refund all users (I don't know if this particular case has been resolved by now, though). They admitted that it was their fault. The problem has been solved. Of course, the warning "use it at your own risk" still applies. It probably applies for every bitcoin client. I'm not saying something similar cannot happen again.

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Poor seeding of RC4 (with only 256 possible seeds)
Generate a sequence of numbers with each seed (a sequence length of 256 should be sufficient)

A sequence length of 256 is not sufficient

I went more than 10 times further and even then I missed a few values that I added later.
But 256 would have been enough to find half of the money if you also attacked the signatures.

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Searching for matches against (Hash 160) hashes:
...
208 = d2d703c8dd35e380a3c7b647391556af18fef5ed
...
246 = fe742cdfbc52ba07479f0b84eaf1a17eab016de2
...

BTW, 208 is the address 1LDpUmrwVKSFyXy2czE423dH8yd4K9R9WW that was emptied first.