Senior Security Engineer (Blockchain Security)

TL;DR

Senior Security Engineer (Blockchain Security): Ensuring the security of crypto operations by implementing an offensive security mindset and building internal security tooling with an accent on vulnerability discovery and regulatory compliance. Focus on designing secure blockchain architectures, automating security reviews, and integrating AI-assisted engineering into the security lifecycle.

Location: Hybrid (Brazil: São Paulo, Campinas, Rio de Janeiro, Belo Horizonte)

Company

Nu is one of the largest digital financial platforms in the world, redefining financial services across Latin America.

What you will do

• Apply an offensive security mindset through penetration testing, attack simulations, and vulnerability assessments of crypto products.
• Drive product security via threat modeling, security-by-design reviews, and embedding secure practices into the SDLC.
• Build and operate in-house security services including hardened ingress, monitoring/alerting systems, and secure secret-management.
• Ensure crypto operations meet financial regulatory requirements and support audits by producing necessary evidence.
• Collaborate with engineering teams to design secure blockchain architectures for new products.
• Utilize AI to build tools for threat modeling, code review, and attack simulation.

Requirements

• Strong background in product or offensive security, including penetration testing and incident response.
• Experience with secure SDLC, threat modeling, and security-by-design reviews.
• Hands-on software engineering ability to build security automation; willingness to learn Clojure.
• Solid working knowledge of blockchain fundamentals, wallets, keys, and smart contracts.
• Familiarity with AWS and a strong grounding in operating systems, networks, and infrastructure architecture.
• English: Proficiency required for clear written and spoken technical communication.

Nice to have

• Deep knowledge of consensus algorithms, cryptographic protocols, and smart contract internals.
• Experience auditing Solidity smart contracts or working with DeFi protocols.
• Experience integrating with third-party crypto custody providers like Fireblocks or Circle.
• Certifications such as OSCP, OSWE, or Certified Blockchain Security Professional.

Culture & Benefits

• Opportunity to earn equity at hirify.global.
• Comprehensive health benefits including medical and dental plans.
• NuCare program for psychological, financial, and legal assistance.
• 30 days of paid vacation and extended parental leave.
• Work-from-home allowance and meal/transportation benefits.
• Relocation assistance package if applicable.