‘Big Spender’ Bitcoin Wallet Exploit Is an ‘Issue With BTC Itself’, Says BCH Supporter

A crypto security firm has identified a double-spend exploit targeting popular bitcoin wallet providers. 

According to a report by ZenGo, the security firm has discovered a double and multiple spend wallet exploit for bitcoin dubbed “BigSpender.” The report claims the exploit allows an attacker to cancel a bitcoin transaction but still have it appear in a victim’s vulnerable wallet. 

The report reads, 

The core issue at the heart of the BigSpender vulnerability is that vulnerable wallets are not prepared for the option that a transaction might be canceled and implicitly assume it will get confirmed eventually.

As CryptoGlobe reported, ZenGo found that a user’s balance would be increased following an unconfirmed incoming transaction, without a subsequent decrease in the event the transaction being double-spent. The firm outlined how an attacker could use the exploit to cancel transactions of sent bitcoin while still receiving goods and services in return. 

The security firm tested nine popular cryptocurrency wallets and found BRD, Ledger Live and Edge to be vulnerable to the exploit. All three companies were notified by ZenGo of the threat and subsequently updated their products. However, the firm noted that “millions” of crypto users may have been exposed to the attack prior to the update. 

Bitcoin Cash supporter Hayden Otto told Cointelegraph the exploit is particularly concerning for bitcoin-accepting merchants. 

He said, 

The technique is facilitated by RBF (replace by fee), a so-called ‘feature’ added at the protocol level by the Bitcoin Core developers.The issue exists if you use BTC. Wallet software can only make some trade off, which results in a worse BTC user experience, in order to try to protect BTC users.

Otto claimed the exploit was derived from “an issue with BTC itself” and had little to do with wallet software. 

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