Get the Crypto Payment Security & Compliance Playbook
Back to Blog

The Initial Analysis of the bZx Security Incident

Code Auditing
November 6, 2021

On Nov 5th, bZX protocol was reported hacked. The attacker drained tokens in the affected smart contracts. After the initial analysis of the attack transactions, we suspect it’s due to the compromised private key of the developer.

Attack process

The process is roughly simple. The privileged function transferOwnership is invoked to transfer the ownership of affected smart contract to a new one, e.g., 0x0acc0e5faa09cb1976237c3a9af3d3d4b2f35fa5. Then the new contract owner can transfer all the tokens that have been approved to the smart contract to arbitrary addresses.

Note that, the privileged function transferOwnership can only be invoked by the current owner of the smart contract. Indeed, we find the caller of this function is 0xb7f72028d9b502dc871c444363a7ac5a52546608, which is the contract creator of the affected smart contract.

We do not know the exact reason why the contract creator transfers the ownership to other addressees. However, we suspect it’s due to the compromised (or leaked) developer private key.

Conclusion

In summary, the security of the private key of DApps is essential to the security of the application, especially for the ones that are not using DAO. We suggest that the project owner can use some new techniques such as confidential computing and MPC to secure the private key.

About BlockSec

BlockSec is a pioneering blockchain security company established in 2021 by a group of globally distinguished security experts. The company is committed to enhancing security and usability for the emerging Web3 world in order to facilitate its mass adoption. To this end, BlockSec provides smart contract and EVM chain security auditing services, the Phalcon platform for security development and blocking threats proactively, the MetaSleuth platform for fund tracking and investigation, and MetaSuites extension for web3 builders surfing efficiently in the crypto world.

To date, the company has served over 300 esteemed clients such as MetaMask, Uniswap Foundation, Compound, Forta, and PancakeSwap, and received tens of millions of US dollars in two rounds of financing from preeminent investors, including Matrix Partners, Vitalbridge Capital, and Fenbushi Capital.

Official website: https://blocksec.com/

Official Twitter account: https://twitter.com/BlockSecTeam

Sign up for the latest updates
Web3 Attack Surfaces: A Penetration Testing Overview
Security Services

Web3 Attack Surfaces: A Penetration Testing Overview

Crypto institutions keep every traditional attack surface and add the money-handling chain on top of it. This article gives testers a practical abstraction of the running system: a four-component model—Application, Authorization and Signing, Blockchain Interaction, and Infrastructure—with each component's responsibility, representative implementations, and inherited attack surfaces. It then structures web3-specific coverage into five attack-surface areas, from production and automation operations through signing intent, approval and withdrawal chains, and fund logic to on-chain transactions and deployed contracts.

~$23M Lost: Cosmos EVM, Moonwell Exploits | BlockSec Weekly
Security Insights

~$23M Lost: Cosmos EVM, Moonwell Exploits | BlockSec Weekly

During the reporting period (2026/08/22 - 2026/08/30), we cover 5 blockchain security incidents totaling approximately $22.7M in losses; an estimated $74M-$119.5M was drained from Tectonic, most of it erased when Cronos was rolled back to its pre-exploit state. The highlight is a six-chain Cosmos EVM exploit series (~$5.7M realized), traced on TAC Chain, where a shared balance-synchronization bug chained an underflow and an overflow to drain a staking pool. The report also analyzes Moonwell's combined collateral-accounting and oracle price manipulation, Tectonic's combined oracle-price and receipt-token exchange-rate manipulation of low-liquidity collateral, an Ajna liquidation business-logic flaw, and a Rain Card Contract Exploit Series with an Ed25519 signature-verification bypass (Avici, Tria, and others) on Solana.

Rules of Engagement and Production Safety for Institutional Blockchain Penetration Testing
Security Services

Rules of Engagement and Production Safety for Institutional Blockchain Penetration Testing

A penetration test that touches signing, withdrawal, and ledger systems is prepared before it runs. This article follows the engagement lifecycle: turning a business decision into objective, scope, named owners, and authorized access; recording authority, permitted techniques, operating limits, prohibited activity, communications, and evidence handling in a Rules of Engagement document; and protecting live service with measurable stop criteria, monitoring, change coordination, and named pause authority. It closes with the remediation and retest that turn findings into validated controls.

Best Security Auditor for Web3

Validate design, code, and business logic before launch. Aligned with the highest industry security standards.

BlockSec Audit
The Initial Analysis of the bZx Security Incident