Staff Application Security Engineer

OverviewStaff Application Security Engineer role at LEDN. Ledn is a global financial services company built for digital assets. We offer lending, savings and trading products to digital asset holders in over 150 countries. Our team is diverse and focused on democratizing access to the global economy through Ledn's products and services. 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 Bitcoin-backed loan platform. This role drives 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 evolve the authentication layer toward modern, phishing-resistant approaches. You will also design and operate AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated environments. This is a hands-on engineering role with direct impact on product security, infrastructure security, and customer trust. 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. Remediate vulnerabilities and improve secure development practices in collaboration with engineers. 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. 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. Remediate vulnerabilities identified in penetration test reports. Strong communication and collaboration skills, able 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 & Ideal CandidateWe seek a leader who thrives in a startup or tech environment and embodies our values: integrity, ownership, progress, and empathy. Have a passion for progress, adaptability, resilience, and comfort navigating ambiguity in a high-growth setting. Builder mindset, eager to create, iterate, and scale IS practices. Collaborative, able to influence across functions and cultures with empathy and clarity. Demonstrate integrity and accountability for confidential information across legal contexts. Experience working in a remote environment. Compensation & BenefitsComprehensive total rewards package starting on day one. Competitive PTO and ownership in the company via equity. Remote work flexibility up to 180 days per year (subject to restrictions). Purposeful work in a role that supports company growth and the digital economy. Inclusive, diverse workplace; EEO commitment and confidential accommodation requests throughout recruitment. Location: Caxias do Sul, Rio Grande do Sul, Brazil. We encourage applicants globally and welcome diverse perspectives. No agencies or recruiters, unsolicited resumes will not be accepted. #J-18808-Ljbffr