Security Engineer

Overview Security Engineer role at LEDN is a hands-on engineering position focused on application security, authentication/identity, and confidential computing. The role strengthens the security of our Bitcoin-backed loan platform and drives both tactical improvements and long-term strategy for securing applications and authentication systems. The team works with JavaScript/TypeScript services, AWS serverless stack (Lambda, API Gateway, Cognito, SNS, SQS), MongoDB and Kubernetes microservices, and evolves the authentication layer toward modern, phishing-resistant approaches. The role also involves designing and operating AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated, verifiable environments. This is a product- and infrastructure-facing role with direct impact on security and customer trust. Responsibilities Lead secure design and code reviews across engineering teams. Define and enforce secure coding practices for JavaScript/TypeScript services. Automate vulnerability detection (SAST, SCA, DAST) within CI/CD. Conduct threat modeling and risk assessments for new features. Partner with engineers to remediate vulnerabilities and improve secure development practices. Own the roadmap for authentication and identity across customer and internal applications. Enhance Cognito-based identity architecture with stronger, phishing-resistant MFA solutions (e.g., WebAuthn, passkeys, hardware tokens). Collaborate with Product to align usability, compliance, and security in authentication flows. Define secure approaches to session management, device trust, and account recovery. Design enclave-based architectures to isolate and protect sensitive workloads using AWS Nitro Enclaves; migrate high-value operations into enclave environments. Integrate Nitro Enclaves with KMS and secure APIs; ensure compliance, auditability, and resilience of enclave workloads. Harden AWS services (Lambda, API Gateway, SQS, SNS) with least-privilege IAM and secure key management. Improve Kubernetes security posture (RBAC, pod security, image scanning, runtime monitoring). Deploy and operate a SIEM framework; develop detection rules, dashboards, and incident playbooks. Support compliance initiatives (SOC 2, ISO 27001) with security controls and documentation. Qualifications 10 years minimum of proven experience in Application Security with a focus on web and cloud-native applications. Strong knowledge of JavaScript/TypeScript/Golang/Python and modern web vulnerabilities (OWASP Top 10, auth bypasses, business logic flaws). Expertise with AWS security best practices, particularly in serverless architectures. Hands-on experience with AWS Nitro Enclaves for confidential computing. Deep understanding of authentication and authorization standards (OAuth2, OIDC, WebAuthn, FIDO2). Practical experience with Cognito / Auth0 (MFA, custom flows, secure session handling). Background in SIEM design and log correlation across cloud and application layers. Familiarity with Kubernetes security (RBAC, pod security, admission controls, image scanning). Experience with Secure Code Review and understanding of software supply chain. Deep understanding of Linux internals; ability to remediate vulnerabilities identified in penetration tests. Strong communication and collaboration skills, able to influence engineering and product teams. Nice To Haves Familiarity with Bitcoin custody and key management practices. Knowledge of Infrastructure as Code security (Terraform, AWS CDK). Prior work on user-facing security features such as passwordless authentication, recovery flows, or device trust. Culture Fit Leadership mindset, adaptable and resilient in a startup or tech environment; values-driven collaboration. Builder mindset to create, iterate, and scale IS practices. Ability to influence across functions and cultures with empathy and clarity. Integrity and accountability in managing confidential information across diverse contexts. Experience working in a remote environment. What We Provide Growth opportunities and a comprehensive total rewards package starting on day one. Competitive PTO and ownership in the company through shared equity. Remote-friendly policy allowing work from anywhere in the world for up to 180 days (subject to restrictions). A purpose-driven career and an inclusive, diverse workplace. Additional Information Ledn is remote-first and globally distributed; we support inclusive hiring and equal opportunity employment. Please note that due to high application volumes, only qualified applicants will be contacted. Shortlisted candidates may be asked to submit a short video response; we may review publicly available social media activity relevant to the role. No agencies or recruiters; unsolicited resumes are not accepted. Location: Passo Fundo, Rio Grande do Sul, Brazil (Remote-friendly) #J-18808-Ljbffr