How much was lost in the Horizon Finance hack?

The Horizon Finance hack resulted in $25K in losses on March 18, 2021.

What attack technique was used in the Horizon Finance exploit?

The Horizon Finance exploit utilized Rugpull. 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.

Horizon Finance Hack

TOTAL LOST $25K

Low Mar 18, 2021 Rugpull binance

Affected Chain binance Incident surface

Recovered - No recovery reported

All-Time Rank #1858 By amount stolen

Auditors 1 Prior security audit

Incident Overview

The contract deployer added initial liquidity at:

https://bscscan.com/tx/0x8ff11f8a…41322c

Liquidity was removed by the contract deployer at:

https://bscscan.com/tx/0xec15f76f…9b6746

Incident Report

Protocol / Project Horizon Finance

Date of Incident March 18, 2021

Affected Chain(s) binance

Attack Technique Rugpull

Classification Other

Primary Source View Post-Mortem

Protocol Information

Protocol Type Algo-Stables

Affected Token HRZN

Official Website horizonfinance.app/

Protocol Twitter/X @Horizon2021

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 rugpull and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in Horizon Finance's contract logic - root cause: other

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? Hard to catch — private key / OpSec failures are outside smart contract audit scope

Audited by Audit Report 1 — still lost $25K. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Horizon Finance, these are the critical security checks that could have prevented this incident (March 2021).

Verify all logic paths related to Rugpull 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://archive.ph/zVPJ8
02
Web Archive https://web.archive.org/web/20210317233854/https://horizonfinance.app/

Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Other
Year 2021

Learn to Prevent the Next Horizon Finance

The Horizon Finance hack is one of many attacks that skilled auditors are trained to detect before deployment. Master real exploit patterns and defense techniques with hands-on Web3 security training.

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