Old USDC Approval Leads to $340K Exploit via Proxy Contract
A 2020 USDC approval enabled a recent $340K exploit. Users should check wallets and revoke outdated permissions.
- An old USDC approval enabled a new $340K exploit
- CertiK identifies proxy contract as exploit vector
- Users urged to revoke unused wallet permissions
Blockchain security firm CertiK has reported a recent exploit involving a proxy contract address (0x0689…4B43) that drained approximately $340,000 from user wallets. The source of the breach? A USDC token approval granted all the way back in 2020.
This incident highlights the persistent risks associated with leaving old token approvals unchecked. When users approve a smart contract to spend tokens on their behalf, that permission remains active indefinitely—unless manually revoked.
What Happened in the $340K Exploit?
According to CertiK, the attacker exploited a proxy contract that had lingering permissions from years ago. Specifically, the affected wallets had previously approved USDC token transfers to this contract. These outdated approvals enabled the attacker to drain funds without needing any new interaction from the wallet holders.
It’s a chilling reminder that smart contracts can be upgraded or repurposed in malicious ways—especially proxy contracts that separate the logic and data layers. If an attacker gains control of the logic, they can execute arbitrary commands using the permissions already granted.
How to Stay Safe: Revoke Unused Permissions
Crypto users are strongly advised to review and revoke outdated approvals regularly. Free tools like Etherscan Token Approval Checker or Revoke.cash can help identify and remove unnecessary allowances.
Even if your wallet seems safe today, an old approval could make it vulnerable tomorrow—especially if the smart contract it points to is compromised or upgraded by a malicious actor. Regular maintenance of your wallet permissions is just as important as keeping your private keys secure.
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