On May 24th 2022, the Hackerdao (Hackerdao) token was exploited by flashloan attacks, causing a loss of around 200 BNB, which was approximately ~$65,000 at the time of the incident. The stolen BNB was transferred to Tornado Cash immediately afterward.
At approximately 6:43:50 AM UTC on May 24th 2022, address 0xcfc591 attacked token contract Hackerdao (Hackerdao) via flashloan. There is still not much is known about the Hackerdao project as we write this months later, since the social channels were and are still unknown at time of writing. Despite no social channels, the project has managed to accrue an impressive 38,127 holders. This could potentially be a sign of bot activity on the contract. The project activity on-chain has ceased in the past month, likely due to the long slow death of the project post attack.
The attacker made use of the extra fee charge mechanism of the Hackerdao token contract and the skim mechanism of the pairing pools to manipulate multiple Hackerdao token related pools and drained funds from the pools. As a result the Hackerdao attacker gained approximately ~200BNB worth roughly $65,000 USD at the time of the attack. The incident is a valuable lesson to look back on as the attack vector is unique and could have been avoided with contract auditing.
The following attack flow is based on the transaction: https://bscscan.com/tx/0x04673c95054247588bb8380dbc7d361f08f8f0baa319366f48ad46e51d08422d.
Because Hackerdao charges an extra fee if the recipient is the Hackerdao - USDT pool, the Hackerdao - WBNB pool has to pay more than it received, which led to the result that the Hackerdao - WBNB pool has only 61 Hackerdao after "skim", while the number was 1,020 before "skim".
In the Hackerdao token contract, there is a special logic when recipient is the Hackerdao - USDT pool. The contract will charge an extra fee in the transfer process. Attackers can make use of the functionality and the skim mechanism of UniswapV2Pair contract to drain funds from other pools.
Attacker address: https://bscscan.com/address/0xcfc591db031b760961fe8943a183741ed7cd1f82
Hackerdao token contract: https://bscscan.com/address/0x94e06c77b02ade8341489ab9a23451f68c13ec1c
Attacked pool (Hackerdao - WBNB pool): https://bscscan.com/address/0xcd4cdaa8e96ad88d82eabddae6b9857c010f4ef2
The profit is around 200 BNB (around $65K). It was deposited to Tornado Cash.
After completing their malicious flash loan attack and depositing the ~200 BNB into Tornado Cash, the address has shown no signs of life since. Furthermore, the Hackerdao project has seen massive reductions in activity and at time of writing has seen only 5 transactions in the past 30 days. This attack highlights an ongoing problem within the ecosystem of smaller token projects where if there exists a vulnerability it will be exploited and more often than not, destroy momentum of the project. With contract auditing, many of these projects could grow without the growing pains of contract vulnerability. Get audited today!