How much was lost in the Nuls hack?

The Nuls hack resulted in $480K in losses on December 23, 2019.

What attack technique was used in the Nuls exploit?

The Nuls exploit utilized Signature Verification Flaw. 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.

Nuls Hack

TOTAL LOST $480K

Low Dec 23, 2019 Signature Verification Flaw nuls

Affected Chain nuls Incident surface

Recovered - No recovery reported

All-Time Rank #1244 By amount stolen

Year 2019 Incident year

Incident Report

Protocol / Project Nuls

Date of Incident December 23, 2019

Affected Chain(s) nuls

Attack Technique Signature Verification Flaw

Classification Input Validation

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 signature verification flaw and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in Nuls's contract logic - root cause: input validation

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 Signature Verification Flaw audit checklist and test coverage

If you're auditing a protocol with similar architecture to Nuls, these are the critical security checks that could have prevented this incident (December 2019).

Verify all logic paths related to Signature Verification Flaw 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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Threat Assessment

Severity Level

LOW

Attack Vector Signature Verification Flaw
Root Cause Input Validation
Year 2019

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Incident Report

What the Attacker Needed to Succeed

What Auditors Should Check

Related Hacks - Signature Verification Flaw

Learn to Prevent the Next Nuls