Staff Application Security Engineer

OverviewStaff Application Security Engineer at LEDN. Ledn is a global financial services company built for digital assets, providing lending, savings and trading products to digital asset holders in over 150 countries. The role focuses on strengthening the security of Ledn's Bitcoin-backed loan platform, with deep expertise in Application Security, Identity & Access Management, and Confidential Computing. Security is fundamental to protecting customers and the business. This hands-on engineering role will impact product security, infrastructure security, and customer trust, working across JavaScript/TypeScript services, AWS serverless stack (Lambda, API Gateway, Cognito, SNS, SQS), MongoDB and Kubernetes microservices. The role also involves designing and operating AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated, verifiable environments. ResponsibilitiesLead 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. Qualifications10 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; able to remediate vulnerabilities from penetration tests. Strong communication and collaboration skills to influence engineering and product teams. Nice To HavesFamiliarity 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 &BenefitsWe’re looking for a leader who thrives in a startup/tech environment and embodies our values: act with integrity, own it, have a passion for progress, and lead with empathy. Competitive total rewards package; comprehensive PTO; equity ownership in the company. Remote-friendly policy, with up-to-180 days remote work worldwide (subject to restrictions). A purpose-driven career that supports growth and removing barriers to doing what you love. Equal opportunity employer; inclusive and diverse environment. Accommodation requests are addressed confidentially. Location & Application NotesJoinville, Santa Catarina, Brazil; Araquari, Santa Catarina, Brazil. Due to high application volume, 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. No agencies or recruiters, please. #J-18808-Ljbffr