Crypto exchanges suspend Ethereum-based tokens after smart contract bugs detected
Most exchanges have lifted the ERC-20 suspensions, although some functions still remain unavailable.
A number of cryptocurrency exchanges have ceased trading multiple ERC-20 tokens after bugs were discovered inside ethereum-based smart contracts which allowed users to unjustly transfer significant amounts of tokens.
However, at least three of these exchanges have now resumed ERC-20 services, as can be seen in tweets below.
Deposits and withdrawals for ERC-20 tokens have now been re-enabled.
— Poloniex Exchange (@Poloniex) April 25, 2018
Huobi Pro now has lifted the suspension of the deposit and withdrawal of non-ERC20 tokens.
We will be announcing via another announcement for ERC20 tokens' suspension lifting. We apologize for any inconvenience caused during this period.
Details, visit https://t.co/7rF3HdgAsX
— Huobi Pro (@Huobi_Pro) April 25, 2018
Dear traders, the ERC20 deposits are back online. The transfers are still disabled for an inspection. The transfers will be getting online in accordance with the results of the inspection. Please refer to the System Health page (https://t.co/1i1pSWhw7I) for status.
— HitBTC (@hitbtc) April 25, 2018
Cryptocurrency and blockchain publication Coinmonks first reported the existence of a new “batchOverflow” bug in numerous ERC-20 smart contracts on April 22 and the presence of a “proxyOverflow” bug on April 24.
The posts reveal that Coinmonks automated system which analyzes ERC-20 token transfers “raised an alarm” related to two “unusual” and “extremely large” BeautyChain (BEC) token transactions. Coinmonks classified this anomaly as an “in-the-wild” attack that exploited a previously unknown vulnerability in ERC-20 contracts.
“For elaboration, we call this particular vulnerability batchOverflow,” Coinmonks reported.
Our results show that more than a dozen of ERC20 contracts are also vulnerable to batchOverflow. However, with the touted ‘code-is-law’ principle in Ethereum blockchain, there is no traditional well-known security response mechanism in place to remedy these vulnerable contracts.
Coinmonks on the complexities of the batchOverflow bug
Following a system-wide scan, Coinmonks surmised that a substantial number of tokens were affected by the bugs including MESH, BEC, UGToken, SMT, SMART, MTC, FirstCoin, GG Token, CNY Token, CNYTokenPlus.
BeautyChain posted an announcement on its website, advocating that the company will release new smart contracts “as soon as possible”. The project reached an agreement with OKEx Exchange to roll back and cancel any transactions generated after 13:18 on April 22. Purchase of BEC currency will be returned in the same way.
The SmartMesh Foundation said that it would take the equivalent amount of SMT to the counterfeit amount and destroy it to make up for the losses caused, and keep the total supply of SMT at the value of 3,141,592,653.
There are several tokens which can be used in conjunction with Ethereum’s blockchain platform. These are separate to ether, Ethereum’s native currency. ERC-20 defines a list of rules for all Ethereum tokens to follow.
MyEtherWallet (MEW), an online app for storing, sending and receiving Ethereum-based digital tokens, was compromised in a phishing attack yesterday morning, with hackers seizing more than $150,000 in user funds.
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