Senior Offensive Security Penetration Tester - Crypto and Digital Assets, Senior Vice President

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

Job summary

Citi Singapore is seeking a highly skilled Cyber Security professional to join its information security team. You will lead penetration testing across blockchain networks, DeFi protocols, and digital asset systems, combining manual and automated methods to identify vulnerabilities.

The role emphasizes smart-contract reviews (Solidity/Rust/Go/Vyper), cryptography concepts, and collaboration with developers to implement robust security controls.

Qualifications

• Background in software development and security, with hands-on experience in blockchain and smart contracts.
• Strong cryptography understanding including symmetric/asymmetric encryption, hashing, and digital signatures.
• Experience developing security scripts for offensive tooling and CI/CD security automation.
• Familiarity with security tools such as Slither, Mythril, Burp Suite, Postman.
• Master’s Degree or PhD with 3+ years in blockchain or a Bachelor’s with 5+ years.
• Passion for offensive security and ethical hacking in blockchain and digital assets.

Responsibilities

• Plan, scope, and execute comprehensive penetration tests against blockchain networks, smart contracts, 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.

Skills

Blockchain security

Smart contracts

Offensive security

Cryptography

CI/CD security

Education

Master’s degree or PhD in relevant field

Bachelor’s degree with 5+ years in blockchain

Tools

Slither

Mythril

Burp Suite

Postman

Job description

Are you interested in growing your career in Cyber Security?

Whether you are an application developer or researcher looking to make the switch into the challenging, yet rewarding, world of information security, or you are an elite white-hat hacker, Citi is the place for you. Our team of world class, talented individuals, who are passionate about security, put their skills to the test every day on a global scale. At Citi, you will be exposed to all sorts of technologies on an enterprise-scale, so hunger for knowledge and research is greatly appreciated and rewarded.

Technology is constantly evolving, and Citi is evolving with it by adopting the latest application frameworks, migrating to cloud-based technologies, and implementing Artificial Intelligence in numerous workflows across the enterprise. Citi’s application penetration testing team is at the forefront of testing and securing each of these solutions and you can make an impact on the next technology to be released.

This team specializes in conducting various types of penetration testing engagements (full end-to-end white-box and/or grey-box testing) against a variety of Citi owned or 3rd party SaaS applications (Web, Mobile, Thick Client, and APIs) leveraging a wide array of technologies from Artificial Intelligence, to Digital Assets, Blockchain, and more traditional application development frameworks. The primary goal would be to secure Citi, its customers, and clients by manually identifying, researching, validating, and exploiting application security weaknesses and misconfigurations.

Core responsibilities include:

• 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.

Who we are looking for:

• 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 Software Development Life Cycle (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.

Job Family Group:

Technology

Job Family:

Information Security

Time Type:

Full time

Most Relevant Skills

Please see the requirements listed above.

Other Relevant Skills

For complementary skills, please see above and/or contact the recruiter.

Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.

If you are a person with a disability and need a reasonable accommodation to use our search tools and/or apply for a career opportunity review Accessibility at Citi.

View Citi’s EEO Policy Statement and the Know Your Rights poster.