November 03, 2023

Analysis of $2.18 Million Loss in Hacker Attack on OnyxProtocol

On November 1, 2023, Beosin EagleEye detected that the oPEPE market contract of OnyxProtocol fell victim to a hacker attack, resulting in a profit of approximately $2.18 million for the hacker.

OnyxProtocol, a branch of CompoundV2, had previously witnessed a $7 million loss due to a similar vulnerability experienced by HundredFinance back in April 15, 2022. This analysis revisits that specific vulnerability.

Key Information


Attack transaction


Attacker address: 0x085bdff2c522e8637d4154039db8746bb8642bff

Attack contracts







Attacked contracts




Vulnerability Analysis 

The attack primarily exploited rounding and exchange rate manipulation, breaching the project's code defenses.

Attack Process 

Preparation phase:


1. The attacker borrowed 4000 WETH as preparatory funds.

2. These funds were converted into roughly 2.52 trillion PEPE.

3. The 2.52 trillion PEPE was distributed among various addresses, completing the attack preparation phase.


Execution Phase:


1. The attacker acquired a small amount of oPEPE and introduced PEPE into the oPEPE market, altering the PEPE balance and manipulating the exchange rate.

2. A substantial amount of Ethereum was borrowed maliciously from other markets.

3. Leveraging rounding and rate manipulation, the attacker used a small oPEPE quantity to liquidate borrowing and reclaim contributed funds.

4. Repeating these steps, the attacker ultimately converted PEPE back to ETH, repaid the flash loan, and secured a profit of 1156 ETH.


Fund Tracking


At the time of writing, Beosin Trace tracking discovered that the stolen funds had been entirely transferred to Tornado Cash.




Following this event, Beosin's security team advises the following measures:


1. Employ reserve ledgers to record asset borrowing situations.

2. Enhance precision to mitigate errors stemming from arithmetic operations.

3. Prior to project deployment, opt for a comprehensive security audit by a professional firm to mitigate security risks.


If you need any blockchain security services, welcome to contact us:

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