Senior Security Engineer (Blockchain Security)

Nu is the leading digital bank in Latin America serving 135 million customers across Brazil Mexico and Colombia. The company has been leading an industry transformation by leveraging data and proprietary technology to develop innovative products and services.

Guided by its mission to fight complexity and empower people Nu caters to customers complete financial journey promoting financial access and advancement with responsible lending and transparency. The company is powered by an efficient and scalable business model that combines low cost to serve with growing returns.

Nus impact has been recognized in multiple awards including Time 100 Most Influential Companies Fast Companys Most Innovative Companies and Forbes Worlds Best Banks.

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The Blockchain Security team sits within the Product Security & Assurance BA part of the Information Technology and Security (ITSec) BU. Our mission is to support the security of Nus crypto the context of Nus global expansion keeping these products secure and demonstrably compliant with financial regulators is a direct condition for our ability to operate and grow.

As a Senior Security Engineer on this team you own the security posture of our crypto operation. You are the person who thinks like an attacker so our products can withstand real ones: finding vulnerabilities before adversaries do embedding product security into how crypto products are designed and built and making sure our controls satisfy both internal risk standards and external regulatory requirements. You wont just run security tools. Youll build and operate the ones that protect our crypto products from hardened ingress and monitoring/alerting systems to secure secret-management and automated security-review tooling. Your work directly protects customer funds and Nus ability to run crypto products at scale.

• Applying an offensive security mindset to our crypto and blockchain products: simulating attacks running penetration tests and security assessments and turning findings into concrete mitigations.

• Driving product security across the crypto portfolio: threat modeling security-by-design reviews and embedding secure practices into the development lifecycle.

• Building operating and improving in-house security services and tooling that integrate directly with our crypto products for example hardened ingress/edge controls security monitoring and anomaly alerting secure secret-management and automated security-review tooling.

• Ensuring our crypto operation meets regulatory requirements: mapping controls to applicable regulations supporting audits and producing the evidence regulators and internal risk teams expect.

• Collaborating with product and engineering teams to design secure blockchain architecture and embed security-by-design into new products.

• Contributing to security policies standards and guidelines that govern blockchain security operations.

• Using AI to raise the leverage and quality of security work: building and running AI-assisted tooling for tasks like threat modeling code and vulnerability review and attack simulation and helping the team push the frontier of what AI-first security engineering looks like.

• Staying current on emerging attack vectors exploits and best practices across product and blockchain security and sharing that knowledge across the team.
  
  

Must have

• Strong product security and/or offensive security background (penetration testing vulnerability assessment attack simulation incident response).

• Experience embedding security into product development: threat modeling secure SDLC security-by-design reviews.

• Hands-on software engineering ability: you can build and operate security services and automation not just use off-the-shelf tools. Comfortable writing production code (we work heavily in Clojure; strong experience in any modern language plus willingness to learn Clojure is fine).

• Solid working knowledge of blockchain and cryptocurrency fundamentals including how blockchains wallets keys and smart contracts work enough to reason about their security (expert-level depth not required but real familiarity is).

• Strong knowledge of recent and past attack vectors and exploits and how to remediate them.

• Experience with security frameworks such as OWASP and the NIST Cybersecurity Framework (CSF).

• Fluency with AI-assisted engineering: using coding agents and LLMs in daily work with good judgment about where they help where they dont and how to review their output critically.

• Familiarity with AWS and solid grounding in operating systems networks databases and infrastructure architecture.

• Ability to work autonomously and proactively strong analytical/problem-solving skills and clear written and spoken English for technical and non-technical audiences.

Nice to have

• Deeper knowledge of blockchain/crypto internals: consensus algorithms cryptographic protocols smart contracts.

• Experience auditing smart contracts (e.g. Solidity) or working with DeFi protocols.

• Experience integrating with third-party crypto custody/infrastructure providers (e.g. Fireblocks Circle and similar).

• Exposure to regulatory or compliance requirements in a financial or crypto context.

• Experience with bug bounties and/or CTFs.

• Certifications such as OSCP OSWE or Certified Blockchain Security Professional.

Location for this opportunity

• São Paulo Brazil

• Campinas Brazil

• Rio de Janeiro Brazil

• Belo Horizonte Brazil

• Chance of earning equity at Nubank

• Food/ Meal Card (Vale-Refeição and/or Vale Alimentação)

• Public Transportation Commuting Benefit (Vale-Transporte)

• NuCare Psychological Financial and Legal Assistance Program

• Life Insurance

• Medical Plan

• Dental Plan

• NuLanguage Language Course Program

• Nucleo - Our learning platform of courses

• Extended Parental Leave

• Daycare Allowance

• Parental Consultancy

• Work-from-home Allowance

• Gym Partnerships

• 30 days of paid vacation

• Relocation Assistance Package if applicable