Senior Software Engineer- Windows (Duo)

About this role

## Meet the Team

The Zero Trust OS Logon & Enterprise Applications team at Cisco Duo designs and engineers the foundational low-level authentication software that secures critical Windows and macOS enterprise endpoints across tens of thousands of global organizations. Our team's work sits directly at the frontline of Zero Trust access, ensuring seamless, resilient multi-factor authentication and passwordless logon across enterprise fleets, Active Directory environments, and cloud identity providers. We are a tight-knit, collaborative engineering squad of systems programmers and security specialists who value deep technical rigor, pragmatic problem-solving, and psychological safety. You will tackle high-stakes systems challenges—from low-level Windows Credential Providers and ADFS adapters to cutting-edge passwordless architectures—where the code you write executes at the very core of operating system security.

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## Your Impact

• **Design and implement** high-performance, memory-safe endpoint authentication components and enterprise integrations using Modern C++ (C++17/20) and native Win32 APIs to deliver resilient Zero Trust security at operating system logon.
• **Lead the technical design and hardening** of custom Windows Credential Providers, ADFS MFA adapters, and WTS multi-session services to eliminate authentication latency and prevent credential bypass attacks.
• **Develop automated diagnostic utilities** and robust administrative tooling using PowerShell and WMI/CIM to streamline enterprise-scale deployment and enhance sysadmin manageability.
• **Partner closely** with Product Management, Security Architecture, and Design to author Architectural Decision Records (ADRs) and establish comprehensive automated test pipelines to guarantee zero-regression releases.
• **Mentor peer engineers** through insightful code reviews and technical guidance to foster engineering excellence and accelerate team delivery velocity.

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## **Minimum Qualifications*...