Staff Application Security Engineer

OverviewLedn 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. We offer a suite of egalitarian lending, savings and trading products to digital asset holders in over 150 countries around the world. Security is fundamental to protecting our customers and business, and this role will drive both the tactical improvements and long-term strategy for securing our applications and authentication systems. This is a hands-on engineering role with direct impact on product security, infrastructure security, and customer trust. 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. Security is fundamental to protecting our customers and business, and this role will drive both the tactical improvements and long-term strategy for securing our 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 take ownership of evolving our authentication layer toward modern, phishing-resistant approaches. In addition, you will design and operate AWS Nitro Enclaves to protect critical data and cryptographic operations in isolated, verifiable environments. Note: This is a remote-first environment with global teams and an inclusive culture. 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; 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). 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. 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 FitWe’re looking for a leader who thrives in the startup or tech environment and embodies our values: act with integrity, own it, have a passion for progress, and lead with empathy. Be adaptable, resilient, and comfortable navigating ambiguity in a high-growth, fast-paced environment. Have a builder’s mindset, eager to create, iterate, and scale information security practices. Be a collaborative partner, able to influence across functions with empathy and clarity. Demonstrate integrity and accountability in handling confidential information across diverse legal and cultural contexts. Experience working in a remote environment. What We ProvideComprehensive, best-in-class total rewards package that starts on your first day. A competitive PTO package and ownership in the company through shared equity. Opportunity to work remotely anywhere in the world for up to 180 days (subject to restrictions). A career with purpose and a culture that removes barriers to doing great work. Ledn is an equal opportunity employer committed to inclusivity and diversity. You may reach out to the Ledn team for accommodation requests throughout all stages of the recruitment process. Requests will be addressed confidentially. Application NotesLedn Working Environment: Our team is global and remote-first; please note that due to high 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. We do not accept unsolicited agency resumes and are not responsible for any fees related to unsolicited resumes. #J-18808-Ljbffr