How much was lost in the Kinto Bridge hack?

The Kinto Bridge hack resulted in $1.6M in losses on July 10, 2025.

What attack technique was used in the Kinto Bridge exploit?

The Kinto Bridge exploit utilized ERC1967Proxy Backdoor Hijack. Understanding this attack vector is critical for smart contract auditors and developers building secure DeFi protocols.

How can developers prevent similar smart contract attacks?

Preventing smart contract hacks requires a combination of secure coding practices, thorough security audits, and understanding common attack vectors like reentrancy, oracle manipulation, and access control flaws. Smart Contract Hacking (SCH) provides hands-on training to help developers and auditors identify and prevent vulnerabilities before deployment.

Kinto Bridge Hack

TOTAL LOST $1.6M

Medium Jul 10, 2025 ERC1967Proxy Backdoor Hijack arbitrum

Affected Chain arbitrum Incident surface

Recovered - No recovery reported

All-Time Rank #728 By amount stolen

Auditors 1 Prior security audit

Incident Overview

Kinto is the only Sybil Resistant blockchain with User-Owned KYC and enforced Account Abstraction. 100% focused on finance.

Incident Report

Protocol / Project Kinto Bridge

Date of Incident July 10, 2025

Affected Chain(s) arbitrum

Attack Technique ERC1967Proxy Backdoor Hijack

Classification Protocol Logic

Primary Source View Post-Mortem

Protocol Information

Protocol Type Canonical Bridge

Smart Contract Language Solidity

Protocol Twitter/X @KintoXYZ

What the Attacker Needed to Succeed

Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.

Technical Knowledge Deep understanding of erc1967proxy backdoor hijack and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

On-Chain Access Ability to interact with arbitrum smart contracts and deploy a custom exploit contract

Protocol Analysis Identification of the exploitable vulnerability in Kinto Bridge's contract logic - root cause: protocol logic

Execution Speed Precise transaction ordering and timing to exploit the vulnerability within a single atomic block

Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Likely — with a thorough ERC1967Proxy Backdoor Hijack audit checklist and test coverage

Audited by Audit Report 1 — still lost $1.6M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Kinto Bridge, these are the critical security checks that could have prevented this incident (July 2025).

Verify all logic paths related to ERC1967Proxy Backdoor Hijack are guarded by proper access controls and input validation
Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs

Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.

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Security Audit History

Audit Report 1 Report

Sources & References

01
Source 1 https://x.com/ramonrecuero/status/1943426114468352006

Threat Assessment

Severity Level

MEDIUM

Attack Vector ERC1967Proxy Backdoor Hijack
Root Cause Protocol Logic
Year 2025

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