Quote from: bcp19 on July 29, 2013, 01:09:33 PM

Quote from: sumantso on July 29, 2013, 12:29:25 PM

Quote from: Arbitrageur on July 29, 2013, 12:13:21 PM

....unless those coins belongs to the attacker now and he's holding them somewhere, they disappeared from BTER but still are in the attacker's possesion, aren't they?

As lamiomni said, a profit happens when you double spend. In the current blockchain the deposit by the attacker would be invalid. So they are still with the attacker (unless they have been spent again).

Some of that TRC deposit may have been withdrawn by Bter users and should have vanished. Since nobody is reporting that it seems a tad fishy. Unless by luck all the withdrawls used other TRCs only.

I think you are not looking at the big picture.

Exchange wallet: 2,000,000 TRC
Attacker sends 120,000 TRC, coins go to his deposit address, then into exchange wallet.
Exchange wallet: 2,120,000 TRC
Attacker converts on site to BTC and withdraws
Exchange wallet: 2,120,000 TRC
Attacker invalidates original blockchain and deposit disappears
Exchange wallet: 2,000,000 TRC

Now, *IF* someone happened to withdraw from the exchange during this brief period, their TRC sent to other sites would disappear, but how often do people transfer out of an exchange?

Not really, since normally blockchain acceptation is weighted with transactions, the attacker's blockchain contains all the transactions except his own (as a node, you have the ability to rejects transactions).