Senior Blockchain Security Penetration Tester

Citi Group; Singapore; On-site; SGD 120,000 - 190,000; Full time

Job summary

Citi is seeking a highly skilled security professional with blockchain and Web3 expertise to join our Information Security team in Singapore. You will plan and execute penetration tests on blockchain networks, review smart contracts in Solidity, Rust, Go, or Vyper, and perform dynamic security assessments of APIs and web technologies.

You will drive remediation with stakeholders, contribute to automation, and stay ahead of emerging attack vectors in digital asset ecosystems.

Qualifications

• Background in both software development and security, with hands-on experience in blockchain, digital assets, and smart contracts.
• Strong understanding of cryptographic concepts, including symmetric encryption, asymmetric encryption, hashing, and digital signatures.
• Experience developing custom security scripts for offensive security tooling and/or CI/CD security automation to shift testing earlier in the SDLC.
• Familiarity with security tools such as Slither, Mythril, Burp Suite Proxy, Postman, and other application or blockchain security testing tools.
• Master's Degree or PhD with 3+ years of professional or research experience in blockchain and the above technical areas, or a Bachelor's Degree with 5+ years of relevant professional experience in blockchain and the above technical areas.
• Passion for offensive security and ethical hacking, with an interest in securing blockchain technologies and digital assets.

Responsibilities

• Plan, scope, and execute comprehensive penetration tests against blockchain networks, smart contracts, decentralized finance (DeFi) protocols, and digital asset custody systems.
• Perform manual and automated source code reviews of smart contracts written in Solidity, Rust, Go, or Vyper to identify logic flaws, reentrancy, front-running, flash loan vulnerabilities, and integer overflows.
• Act as a subject matter expert in offensive information security performing dynamic and manual security assessments on web technologies such as APIs, JavaScript Frameworks, Artificial Intelligence, and Distributed Ledger Technologies.
• Drive remediation by outlining a defense-in-depth approach to business stakeholders and providing strategic solutions to developers on effective preventive and detective security controls.
• Have strong technical writing and presentation skills to report and articulate the vulnerability assessment results to any audience.
• Contribute to the review of internal processes and activities and assist in identifying potential opportunities for improvement and automation.
• Conduct research into emerging attack vectors, zero-day exploits, and novel vulnerabilities unique to Web3 and digital asset ecosystems.
• Must have or be willing to obtain Industry-accredited security certifications such as: BSCP, GWAPT, GPEN, OSCP, OSWE, CISSP, or other related certifications.

Job description

Citi is seeking a highly skilled security professional with blockchain and Web3 expertise to join our Information Security team in Singapore. You will plan and execute penetration tests on blockchain networks, review smart contracts in Solidity, Rust, Go, or Vyper, and perform dynamic security assessments of APIs and web technologies.

You will drive remediation with stakeholders, contribute to automation, and stay ahead of emerging attack vectors in digital asset ecosystems.