Decoding Earning Farm’s $528k Exploit

Updated at: June 18, 20244 Mins Read

Author: QuillAudits Team


On the 9th of August 2023, Earning Farm from Aave protocol was attacked. The attack was made possible by a reentrancy vulnerability. And around $528k was stolen by the exploiter from the exploit.

About Project

Earning Farm is a set of smart contracts that manage crypto assets. To learn more about them, check out their website.

Vulnerability Analysis & Impact

On-Chain Details

Attacker Address: 0xee4b3dd20902Fa3539706F25005fa51D3b7bDF1b

Victim Contract: 0xFe141C32E36Ba7601D128F0C39DEdBE0F6aBb983

Attack Transaction: 0x6e6e556a5685980317cb2afdb628ed4a845b3cbd1c98bdaffd0561cb2c4790fa

The Root Cause

Although the root cause of the attack was reentrancy but a flawed business logic in burning the shares was also responsible for increasing the impact of the attack.

The withdraw() function was the function that the attacker reentered.

The Root Cause

Notice how the withdrawing process is executed before burning the shares.

Upon close analysis a logical flaw was spotted.

  • If the sender has somehow less share than needed to be burnt, then only their balance will be burned.
  • Hence, when updating the balance of the `msg.sender` later, the result of `balanceOf` is already zero.

Attack Process

  • First, the attacker took a FlashLoan of 10k ETH.
attack process1
  • The attacker then deposited 320 ETH into leveraged eth strategy of Earning Farm yield.
attack process2
  • Soon after that, the attacker withdrew the amount resulting in the attacker getting the sent eth.
attack process3
  • The attacker then sent those shares to another contract that he created
attack process4
  • Due to the flawed logic, nothing was burned from the attacker’s balance and he was able to get his original amount back. Then the remaining shares that were sent were also exchanged to execute the heist.
attack process5

Flow of Funds

Here is the fund flow during and after the exploit. You can see more details here.

flow of funds

Attacker’s Wallets

Currently, all the funds residing in a bundle of 4 addresses with the majority of funds in these –



Here is a snippet of one of the wallet address

attacker wallet

After the Exploit

The Project hasn’t acknowledged the attack as of now.

Incident Timelines

Aug-09-2023 07:34:23 AM +UTC – A suspicious transaction was spotted on stETH to/from Aave Protocol.

Aug-09-2023 07:41:59 AM +UTC – Another suspicious transaction was spotted.

Aug-10-2023 02:49:11 AM +UTC – The attacker transferred the stolen funds to multiple different addresses.

How could they have prevented the Exploit?

  • When dealing with business logic, it is crucial to write comprehensive Test Cases.
  • A non reentrant modifier is sometimes not enough to prevent reentrancy. It is important to analyze the flow of the contract and to carefully examine the exit points of the attacker.

Why QuillAudits For Web3 Security?

  • QuillAudits is well-equipped with tools and expertise to provide cybersecurity solutions saving the loss of hundreds of protocols in funds.
  • Our team of highly skilled auditors have secured over 1M lines of code and $30B in amount.
  • Over the course of multiple years, QuillAudits has been proven to be one of the top choices for protocols to get their codebases audited.

Partner with QuillAudits

  • OG Program (Opportunities for Listing Managers, KOLs, Top Advisors and Investors with access to early stage Web3 projects)
  • WAGSI Program(Claim audit credits to avail exclusive discounts on our auditing package, and additional credits for our automated web3 security infra- QuillShield)

Subscribe to our Newsletter

Your weekly dose of Web3 innovation and security, featuring blockchain updates, developer insights, curated knowledge, security resources, and hack alerts. Stay ahead in Web3!