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. The core values are act with integrity always, own it, have a passion for progress, and lead with empathy. This is a full-time role based in Bangkok (relocation provided) with remote-friendly considerations. Security is fundamental to protecting our customers and business. This role will drive both the tactical improvements and long-term strategy for securing our applications and authentication systems, across JavaScript/TypeScript services, AWS serverless stack, MongoDB and Kubernetes microservices. The role includes designing and operating AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated environments. It is a hands-on engineering 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 with 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. 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. 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; understanding of software supply chain; deep understanding of Linux internals. Remediate vulnerabilities identified in penetration tests; strong communication and collaboration skills to influence across teams. Nice to have: familiarity with Bitcoin custody and key management; knowledge of Infrastructure as Code security (Terraform, AWS CDK); prior work on user-facing security features (passwordless authentication, recovery flows, device trust). Culture & Benefits We’re looking for a leader who thrives in startup/tech environments and embodies Ledn values, including adaptability, collaboration, integrity, and accountability. The ideal candidate will be adaptable, resilient, and comfortable navigating ambiguity in a high-growth, fast-paced environment. The company provides a comprehensive total rewards package, competitive PTO, and employee ownership via shared equity; remote-work eligibility for up to 180 days worldwide (subject to restrictions). You may reach out to the Ledn team by emailing for accommodation requests throughout all stages of the recruitment process. Requests will be addressed confidentially. Ledn is an equal opportunity employer and values diversity; no agencies or recruiters please. We do not accept unsolicited agency resumes. #J-18808-Ljbffr