Chinese Exchange Yunbi Lost 40,000 ETC Over Chain Vulnerability

 Yunbi, one of China’s biggest Ethereum trading exchange,  announced today that they were to postpone the listing of ETC in order  to undertake “security preparations” to address vulnerabilities due to  “Relay Attack.”Yunbi further stated that they had lost over 40,000 ETC “from users who deposited ETH before YUNBI listing ETC after Hard Fork:“The major reason of this lost is due to “Relay Attack” during the hard fork. YUNBI will not be responsible for this lost.”After YUNBI lists ETC, please make sure you use the correct address to deposit your ETC and ETH.”The relay attack was described by Péter Szilágyi, one of Ethereum’s core developers, who said:

Think  of transactions [as] an authorization to take X funds off your account.  This authorization is simply a digital signature which currently is  valid on both chains. So if you have funds on both chains, the signature  can move those funds on both chains.

This  vulnerability was well publicized prior to the fork leading some to  suggest that the existence of two chains would not be viable as  transactions can be replayed. However, Poloniex listed ETC regardless,  with other exchanges following, including Kraken, Bitfinex and Yunbi.Gdax  and CHBTC, China’s biggest ETH exchange by trading volume, have stated  that they will not list ETC, but will allow their customers to withdraw  ETC if applicable. Coinbase will likewise not add any ETC functionality  and since ETH was added to Coinbase after the hardfork, there are no ETC  to allocate.The vast majority of Ethereum’s community has shown  support for the forked chain with ETH’s price remaining relatively  stable while the overall ETH plus ETC marketcap has increased  considerably after the fork and after Poloniex’s ETC listing, with ETH  holders being more than 30% richer since the hardfork. Furthermore, the  Ethereum Foundation which employs countless of experienced developers  working on sharding, Casper and other applications has come out in  support of ETH:

We will focus our resources and attention on the chain which is now called ETH (ie. the fork chain)

Ethereum  users and dapp developers can, therefore, fully ignore ETC and be safe  from relay attacks if they transact on only one chain allowing the two  communities to freely co-exist and compete in their chosen path. 

 Source: Crypto Coins News