Approval Hacks & Exploits

On March 20 2024, over $1.8m was stolen from users of an old version of DeFi protocol Dolomite. The exploit was found in an old contract that was deployed in 2019 and had since been discontinued. However, several users still had lingering approvals to this old contract, which the attacker was able to exploit to drain funds from their wallets.

On March 20th 2024, ParaSwap discovered a vulnerability in one of their smart contracts. After discovering this vulnerability, they executed a successful whitehat hack to rescue affected user funds. A few addresses were missed so about $24k of funds ended up being stolen. ParaSwap is working on refunding all affected users shortly.

Over 2 million dollars was stolen from users of decentralised exchange Unizen. Not much is known yet so we will update after a full post-mortem.

Over $6m was stolen from users of DeFi protocol Seneca on Ethereum and Arbitrum. Malicious actors were able to exploit a bug in several smart contracts belonging to the Seneca system. Not much is known about the specific exploit yet and we are still awaiting a full post-mortem.

Over $1.7m was stolen from users of Concentric, a DeFi protocol on Arbitrum. The attackers were able to gain access to the protocol's admin keys, which they used to execute malicious upgrades on the protocol's contracts - allowing them to drain the wallets of any users that had active token approvals for the protocol.

Over 3 million dollars was stolen from users with active token approvals to cross-chain bridge provider Socket. Socket is the underlying technology used by several bridges, such as the popular Bungee Exchange and Rainbow Wallet's bridge functionality. If you've used any of these bridges in the past, you may be affected.

Close to $2M worth of NFTs has been stolen from users of the NFT fractionalization platform Floor Protocol on the 17th of December, mostly Bored Apes and Pudgy Penguins. The vulnerability was patched by the team, preventing further losses, which could have been over 10x larger.

Close to $3M worth of NFTs was stolen from users of the peer to peer platform NFTTrader, mostly made up of Bored Apes and Mutant Apes. The main exploiter discovered a reentrancy bug in multiple old contracts of NFT Trader, allowing them to drain users' approved assets. Multiple other exploiters followed suit. Representatives from Yuga Labs and Boring Security DAO have since successfully negotiated with the main exploiter to return the assets in return for a 10% bounty. Several hundreds of thousands of dollars worth of NFTs is still in the hands of other exploiters.

Over $600k has been stolen from users of many different crypto websites, including SushiSwap and Revoke.cash. This hack is a result of a vulnerability in the Ledger Connect Kit library, which is used by many crypto websites to connect to Ledger hardware wallets. The vulnerable library allowed hackers to inject a malicious script into these popular crypto websites. Many websites, like SushiSwap and Revoke.cash were quick to take their websites offline and remove the affected library. Most big websites were able to remove the library within a few hours, but some websites took longer to mitigate the issue. Because it is not known how many websites were affected, we recommend to check if you're affected by this hack if you used any crypto websites on the 14th of December 2023.

Over $600k has been stolen from users of Unibot, an automated Telegram trading bot. The team had released a new version of their router contract on October 28th, which was exploited on October 31th 2023. The Unibot team has since refunded all the affected users.

Over $500k has been stolen from users of Maestro, an automated Telegram trading bot. The team had released a new version of their router contract on October 13th, which was exploited on October 25th 2023 due to misconfigured permissions on some of the smart contract's functionality. The Maestro team quickly issued a fix for the smart contract bug by upgrading their upgradeable router contract. All affected users that lost funds in the exploit were reimbursed for their losses. Because the router contract was upgraded, it is not necessary to revoke your approvals to this contract, but you may do so if you wish.

Over $270k was stolen from users of Galxe, a popular Web3 community building platform. Hackers were able to gain access the platform's DNS settings through social engineering after which they pointed the DNS records to a malicious website that they controlled. Any users who interacted with the Galxe website on the 6th of October 2023 may be at risk.

Over $180k was stolen from users of CivFund. It is still uncertain how the hack happened because the smart contract is not open source, but it is likely that there was an issue with access control allowing the attackers to call privileged functions, and steal approved user funds in the process.

Over $120M was stolen by hackers that exploited the Multichain MPC wallets. As of now it is unclear how this compromise happened. No approved user funds have been stolen, but the Multichain team has recommended revoking approvals due to the uncertainty of the exploit.

Over $850k was stolen from liquidity providers of Biswap, a decentralized exchange on BNB Chain. Biswap recently launched their v3, and the team created a migrator contract to help users migrate their liquidity from v2 to v3. The migrator contract lacked proper access control, and an attacker was able to call the migrator contract to steal funds from liquidity providers. The Biswap team has started reimbursing affected users.

About $100k was rescued from a vulnerable contract of Unagii, an Ethereum DeFi yield aggregator. The funds were rescued from the vulnerable contract by the Unagii team, but close to $60k was still taken from a single user by an automated MEV operator. The Unagii team has since reimbursed all the affected users.

Over $600k was rescued from deprecated contracts of decentralised exchange Hashflow. A whitehat hacker created a contract to rescue the funds and return them to the rightful owners. Users of Hashflow are advised to revoke all approvals to these deprecated contracts before claiming their rescued funds. Some user funds were still stolen by black-hat hackers after the initial rescue though.

Over $2.5M was stolen from users of Atlantis Loans, a DeFi protocol on BNB Chain. The attacker created a malicious governance proposal that maliciously updated the contracts of several contracts in the system. These updated smart contracts were then used to drain approved user funds.

Over $3.5M was stolen from users of the popular DEX SushiSwap. The vulnerability only concerns a recently deployed SushiSwap contract, so only users who interacted with the exchange between the 1st and the 9th of April are affected.

Over $8.2M was stolen from users of BSCex / SwapX, a DEX on BNB Chain. Vulnerabilities were found in four old contracts belonging to the DEX. Many users still have active approvals to these contracts, even though they haven't used it for a long time.

Over $700k has been stolen by Harvest Keeper from their users. Harvest Keeper claimed to be an "AI-powered" trading platform that provided unsustainably high yields, but turned out to be a scam. When they rugpulled they didn't just steal the deposited funds, but also all approved user funds.

About $30k was stolen from users of Revert Finance. Hackers were able to execute arbitrary code from the context of the vulnerable contract, allowing them to transfer approved user funds.

Over $2M was stolen from users of Dexible, a DEX aggregator. Hackers exploited a vulnerability that allowed them to provide their own Router contract, which they programmed to steal all approved user funds.

Over $1.4M was stolen from the users of cross-chain DEX Rubic. Hackers were able to exploit active approvals because the USDC contract was mistakenly added as a whitelisted "Router contract". The Rubic team has compensated affected users.

Around $7k was stolen from a select number of users of Polynomial Protocol, a derivatives platform on Optimism. Since this contract was no used for all functionality, only a few users were affected. Polynomial Protocol reimbursed the affected users.

Around $90k was stolen from users of Brahma, a cross-chain DeFi protocol. Hackers were able to exploit a vulnerability due to incorrect access control.

Over $1.1M was stolen from users of the BitKeep Wallet. Hackers were able to abuse unlimited approvals to steal approved user funds on BNB Chain and Polygon. The BitKeep team reimbursed affected users.

About $200k was stolen from users of the Rabby Wallet. Only users who used the wallet's Swap function and have active approvals are at risk.

Over $21M was stolen from users of Transit Swap, a DEX on Ethereum and BNB Chain. Any wallets with active approvals to these smart contracts are at risk.

Over $200k was stolen from users of Celer. Hackers were able to compromise their official website and inject malicious code into it. This malicious code requested users to grant unlimited approvals to the hackers' wallets.

Over $500k was stolen from users of the popular DEX Curve. Hackers were able to compromise their official website and inject malicious code into it. They injected malicious approval transactions into the frontend, draining users' wallets. Anyone that interacted with the Curve frontend on the 9th of August is at risk.

Over $400k was stolen from users of PREMINT, a popular NFT platform. Hackers were able to compromise their official website and inject malicious code into it. This malicious code requested users to grant unlimited approvals to the hackers' wallets.

Over $200k was stolen from users of Quixotic, an NFT marketplace on Optimism. The contract allowed malicious actors to sell worthless NFTs to victims for high prices due to missing signature verifications. The smart contract is now paused, but it is still recommended to revoke approvals.

Over $500k was stolen from users of several popular dapps, including Convex, Ribbon, and DeFiSaver. Hackers were able to access these websites' Namecheap settings to inject malicious code into the websites. This malicious code requested users to grant unlimited approvals to the hackers' wallets.

Over $2.5M was rescued from a vulnerable Zapper contract. The Zapper team was notified of the vulnerability by whitehat hackers and were able to rescue the approved user funds. After revoking active approvals, users were reimbursed their funds.

Over $1.2M was stolen from users of BasketDAO, a DeFi protocol for creating token baskets. Two of their contracts contained vulnerabilities that allowed hackers to steal approved user funds. Since then, BasketDAO has shut down and was acquired by another DeFi protocol, PieDAO.

Over $700k has been stolen from users of Auctus, a decentralized options protocol on Ethereum. The Auctus team discovered a vulnerability in one of their older Beta contracts, which allowed attackers to drain approved funds from users' wallets.

Around $600k was stolen from users of LI.FI, a cross-chain bridge and DEX aggregator. Hackers exploited a vulnerability that allowed them to execute arbitrary functions from the context of the smart contract, including transactions that drained approved user funds. LI.FI has since then patched the vulnerability and reimbursed affected users.

Over $3M was stolen by hackers that exploited a bug in the contracts of Multichain (formerly Anyswap), a cross-chain swap router. Any wallets that granted approvals to their smart contracts are at risk.

About $26M was rescued from a vulnerable Sorbet Finance smart contract. The team was able to drain all vulnerable funds and has placed it in a special escrow smart contract, where the original owners can reclaim them. Active approvals must be revoked before receiving refunds.

Over $120M was stolen from users of BadgerDAO, a popular DeFi platform. Hackers were able to compromise their official website and inject malicious code into it. This malicious code requested users to grant unlimited approvals to the hackers' wallets.

About $2M was rescued from a vulnerable dYdX smart contract. The team was able to drain all vulnerable funds and has been refunding users once they revoke their active approvals. Despite their efforts, hackers were still able to steal just over $200k, which the dYdX team has reimbursed out of their own pocket.

Over $55M was stolen from users of DeFi platform bXz. Hackers gained access to the private keys of an admin account and deployed a malicious update to bZx' smart contracts. This new code allowed them to drain bZx' contracts and all approved user funds. This was the final nail in the coffin for bZx, which was exploited multiple times before.

Over $27M was stolen from users of StableMagnet, a DEX on BNB Chain. The StableMagnet team built a backdoor into their smart contract that allowed them to drain the funds in liquidity pools and from users with active approvals.

Over $14M was stolen from users of Furucombo, an app that helps users compose DeFi transactions. Hackers were able to trick the Furucombo governance to whitelist a scam contract, which was subsequently able to drain all approved user funds.

About $400k was rescued from a vulnerable Bancor contract. A vulnerability was discovered by the 1inch team and reported to Bancor. Most of the vulnerable funds were saved by the Bancor team, but just over $100k was still taken by automated front-running bots.