KEYTAKEAWAYS
- Bybit lost $140 million in a highly organized hack, exploiting Safe wallet vulnerabilities.
- Attackers used social engineering to manipulate key holders into signing a malicious transaction.
- The Lazarus Group is suspected to be behind the attack, continuing their targeting of crypto platforms.
CONTENT
BYBIT FACES THE LARGEST CRYPTO THEFT IN HISTORY
On the evening of February 21, 2025, the cryptocurrency exchange Bybit was targeted in a well-planned attack, resulting in the theft of approximately $1.4 billion in assets. This attack became the largest theft in cryptocurrency history. The attack was not due to a smart contract vulnerability but exploited the Safe multi-signature wallet system used by Bybit.
The attackers used deceptive tactics to trick several key holders into signing a malicious upgrade transaction, allowing them to take control of the wallet and transfer the funds. Following the incident, blockchain detective ZachXBT, the SlowMist security team, and Bybit’s own team quickly began investigating, revealing technical details of the attack and the likely culprit—North Korean hacker group Lazarus Group.
THE TIMELINE: FROM DEPLOYMENT TO FUND TRANSFER
According to on-chain analysis, the preparation for this attack began at least two days earlier. The attackers first obtained initial funds from an address on Binance (0x0fa09C3A328792253f8dee7116848723b72a6d2e) and then deployed a malicious contract (0xbDd077f651EBe7f7b3cE16fe5F2b025BE2969516) on February 19, 2025, at 07:15:23 UTC.
On February 21, 2025, at 14:13:35 UTC, the attackers tricked three key holders of the Safe wallet into signing a transaction that replaced the original Safe contract with the malicious version. The transaction hash was：0x46deef0f52e3a983b67abf4714448a41dd7ffd6d32d32da69d62081c68ad7882.
This malicious contract contained a backdoor, which used DELEGATECALL to write attack code into storage (STORAGE 0, address 0x96221423681A6d52E184D440a8eFCEbB105C7242). The built-in functions, sweepETH and sweepERC20, quickly transferred assets from the cold wallet.
The stolen assets included 401,347 ETH (around $1.068 billion), 8,000 mETH (about $26 million), 90,375.5479 stETH (roughly $260 million), and 15,000 cmETH (around $43 million), totaling over $1.46 billion. The transfer process was highly efficient. The initial hacker address (0x47666Fab8bd0Ac7003bce3f5C3585383F09486E2) distributed 400,000 ETH in 10,000 ETH batches across 40 addresses. They also converted 205 ETH into BTC via Chainflip, sending it to a Bitcoin address (bc1qlu4a33zjspefa3tnq566xszcr0fvwz05ewhqfq).
Meanwhile, 8,000 mETH and 90,375.5479 stETH were swapped for 98,048 ETH on Uniswap and ParaSwap, and later transferred to another address (0xdd90071d52f20e85c89802e5dc1ec0a7b6475f92) and further spread across nine more addresses. Notably, the 15,000 cmETH was transferred to 0x1542368a03ad1f03d96D51B414f4738961Cf4443, but mETH Protocol temporarily paused withdrawals, recovering that portion of the stolen assets.
THE “BLIND SIGNING” RISK OF SAFE MULTI-SIGNATURE WALLETS
The Safe multi-signature wallet, widely used as a smart contract wallet, operates under the “n-of-m” model (e.g., 3-of-5), requiring multiple key holders to authorize transactions to enhance security. However, this attack exposed its potential weaknesses.
Bybit CEO Ben Zhou pointed out in an X post at 23:44 on the night of the attack that the attackers did not breach the Safe contract directly but instead exploited a frontend interface manipulation. This deceived the signers into approving a malicious upgrade transaction that appeared normal on the interface.
This “blind signing” issue arises because hardware wallets struggle to interpret complex transactions, making it hard for users to verify the true contents of a transaction before signing.
The SlowMist security team speculates that the attackers may have used social engineering techniques to study the internal financial team’s operations at Bybit or even compromised the Safe’s frontend system or the signers’ devices.
This method mirrors similar attacks in 2024, such as those against WazirX (a $230 million loss) and Radiant Capital (a $50 million loss), where Safe multi-signature wallets were replaced with malicious contracts, and the permission check methods were strikingly similar.
NORTH KOREAN HACKERS’ “OLD TACTIC”?
Blockchain detective ZachXBT used transaction testing, wallet correlations, and timing analysis to confirm that the attack was linked to the North Korean hacker group Lazarus Group. This group has increasingly targeted cryptocurrency platforms in recent years, using increasingly sophisticated methods.
Further analysis by SlowMist and Arkham revealed connections between the hacker’s address and previous attacks on exchanges like BingX and Phemex, with the funds showing typical laundering patterns associated with Lazarus Group.
While the initial funds came from Binance, this may have been a strategy to cover the attackers’ tracks, and there is a high likelihood that the accounts used were either unverified or using false identities.
BYBIT’S RESPONSE AND MARKET IMPACT
After the incident, Bybit reacted swiftly. In their official statement, they assured customers that all assets would be backed 1:1, and the platform could cover the loss. User withdrawal functions were not affected. By 10:51 on February 22, Ben Zhou confirmed that deposits and withdrawals had been restored.
However, the $1.5 billion theft certainly served as a wake-up call for the crypto industry. While Bybit was not affected by a smart contract vulnerability, the weakness in its frontend security and operational procedures was clearly exposed.
LESSONS AND FUTURE OUTLOOK
This attack underscores that even a well-established Safe multi-signature wallet cannot fully withstand a meticulously planned social engineering attack. Frontend manipulation, blind signing risks, and unclear operational processes became exploitable weaknesses.
This event is not an isolated case, as Lazarus Group used similar tactics to attack multiple platforms in 2024, including DMM Bitcoin (with a $305 million loss). These cases highlight the need for the industry to shift its focus from single-point technical solutions to comprehensive, end-to-end security measures.
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