In-depth technical analysis of the Bybit hack

[carlospolop]

🤖 Automated Content Update

This PR was automatically generated by the HackTricks News Bot based on a technical blog post.

📝 Source Information

• Blog URL: https://www.nccgroup.com/research-blog/in-depth-technical-analysis-of-the-bybit-hack/
• Blog Title: In-depth technical analysis of the Bybit hack
• Suggested Section: Blockchain & Crypto (or Web Pentesting -> Wallet/dApp signing flows): add a page on 'Web3 signing workflow compromise (EIP-712 tx mutation / blind-signing) + Safe/Gnosis delegatecall proxy takeover via storage-slot collision'

🎯 Content Summary

Context and impact

NCC Group analyzes the Bybit cold-wallet theft on February 21, 2025, where >$1.4B (including 401,347 ETH) was drained. The core issue was not a cryptographic break of multisig, but a signing workflow compromise: Bybit’s signers were shown a benign transaction in Safe{Wallet}, but were tricked into producing valid EIP-712 signatures for a different transaction. That transaction then executed an on-chain delegatecall-based pr...

🔧 Technical Details

1. Targeted Web3 signing deception via compromised dApp JavaScript
   If an attacker can tamper with a wallet/dApp’s delivered JavaScript (supply-chain compromise, build pipeline compromise, or hosted bundle replacement), they can selectively trigger on specific victim wallet addresses/signers and mutate the transaction object only at the last moment (right before the signing call). A common pattern is: clone original tx data (e.g., structuredClone), overwrite security-critical fields (to, data, operation, gas), obtain a valid EIP-712 signature over the attacker-chosen parameters, then restore the original tx object before it is shown/stored so users/other signers believe the signature corresponds to the benign transaction.
   
   2) Proxy takeover via delegatecall + storage-slot collision
   Whenever a privileged executor (multisig/smart wallet) can execute arbitrary delegatecall, an attacker can point ...

🤖 Agent Actions

Updated the Blockchain & Crypto section with a new page on Web3 signing workflow compromise and Safe delegatecall proxy takeover, detailing off-chain EIP-712 transaction mutation and on-chain slot-0 overwrite via delegatecall, plus mitigations and references. Linked it from the main blockchain README and restored the Smart Contract Security section linkage.

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[carlospolop]

🔗 Additional Context

Original Blog Post: https://www.nccgroup.com/research-blog/in-depth-technical-analysis-of-the-bybit-hack/

Content Categories: Based on the analysis, this content was categorized under "Blockchain & Crypto (or Web Pentesting -> Wallet/dApp signing flows): add a page on 'Web3 signing workflow compromise (EIP-712 tx mutation / blind-signing) + Safe/Gnosis delegatecall proxy takeover via storage-slot collision'".

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Bot Version: HackTricks News Bot v1.0