Staff Application Security Engineer

Overview Staff Application Security Engineer. Ledn is a global financial services company built for digital assets, helping to improve the everyday lives of Bitcoin holders while building generational wealth for the future. Ledn offers a suite of egalitarian lending, savings and trading products to digital asset holders in over 150 countries. Our team is diverse and committed to democratizing access to the global economy. Our core values guide how we operate: act with integrity, own it, pursue progress, and lead with empathy. This is a hands-on engineering role focused on securing our Bitcoin-backed loan platform. The Opportunity We are seeking a full-time Staff Application Security Engineer with deep expertise in Application Security, Identity & Access Management, and Confidential Computing to strengthen the security of our platform. Security is fundamental to protecting customers and the business, and this role will drive both tactical improvements and long-term strategy for securing applications and authentication systems. You will work across our JavaScript/TypeScript services, AWS serverless stack (Lambda, API Gateway, Cognito, SNS, SQS), MongoDB and Kubernetes microservices, and will take ownership of evolving our authentication layer toward modern, phishing-resistant approaches. You will design and operate AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated, verifiable environments. This is a hands-on role with direct impact on product security, infrastructure 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 (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; integrate with KMS and secure APIs; migrate high-value operations into enclave environments; 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. What You Bring to Ledn 10+ years of proven experience in Application Security for web and cloud-native applications. Strong knowledge of JavaScript/TypeScript/Golang/Python and modern web vulnerabilities (OWASP Top 10, auth bypasses, business logic flaws). Hands-on experience with AWS security best practices, especially in serverless architectures. Hands-on experience with AWS Nitro Enclaves for confidential computing. Deep understanding of authentication/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; understanding of software supply chain; strong Linux knowledge. Remediate vulnerabilities identified in penetration tests; strong communication and collaboration skills to influence across teams. Nice to Haves Familiarity with Bitcoin custody and key management practices. Knowledge of Infrastructure as Code security (Terraform, AWS CDK). Experience with user-facing security features (passwordless authentication, recovery flows, device trust). Culture Fit We look for a leader who thrives in a startup or tech environment and embodies our values: progress, collaboration, integrity, and accountability. The ideal candidate is adaptable, resilient, and comfortable navigating ambiguity in a high-growth, fast-paced environment; has a builder’s mindset to create, iterate, and scale information security practices; and can influence across functions and cultures with empathy and clarity. Experience working in a remote environment is a plus. What We Provide Ledn is a leading digital asset company offering tremendous growth opportunities, a comprehensive rewards package, and remote-friendly options. We offer a competitive PTO package, ownership in the company through shared equity, and remote-work up to 180 days per year (subject to restrictions). We are an equal opportunity employer and value inclusivity and diversity. We do not accept unsolicited agency resumes. Contact for accommodations throughout the recruitment process: our team can be reached via email for accommodation requests, with confidential handling. We are a global, remote-first team spread across North America, Latin America, South Africa and Europe. Location: Contagem, Minas Gerais, Brazil Note: Due to high volume of applications, only qualified applicants will be contacted. Shortlisted candidates may be asked to submit a short video response and we may review publicly available social media activity relevant to the role. #J-18808-Ljbffr