Lending app Era Lend on zkSync has been exploited for $3.4 million worth of crypto, according to a July 25 report from blockchain security firm CertiK. The attacker used a “read-only reentrancy attack” to drain the funds, which is a type of attack that interrupts a multi-step process and then causes it to continue after a malicious action has been performed. Specifically, a “read-only” reentrancy is one that does not update the state of a contract.
According to the report, the attacker drained funds in two separate transactions using the externally owned account 0xf1D076c9Be4533086f967e14EE6aFf204D5ECE7a. The attacker relied on a vulnerability in “the callback and _updateReserves function” to manipulate a contract into reporting old values that had not yet been updated.