Senior Software Engineer- Windows (Duo)

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. 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. Minimum Qualifications Bachelor's degree in computer science, computer engineering, or a related technical field (or equivalent practical experience). 6+ years of professional systems software engineering experience using Modern C++ (C++14/17/20) or C. Experience developing native Windows desktop or server applications using Win32 APIs, multi-threading synchronization primitives, and IPC. Experience administering or integrating with on-premises Active Directory (AD DS), Kerberos authentication protocols, or Windows Server environments. Experience authoring PowerShell scripts or utilizing WMI/CIM for Windows system automation, configuration, and troubleshooting. Preferred Qualifications Custom Credential & Security Architecture: Direct experience developing custom Windows Credential Providers, LSA authentication packages, or Active Directory Federation Services (ADFS) MFA adapters. Diagnostics & Low-Level Debugging: Hands-on experience debugging user-mode crashes, race conditions, and deadlocks using WinDbg, ETW tracing, or Visual Studio diagnostic tools. Enterprise Deployment Engineering: Experience authoring enterprise MSI installer customizations, Group Policy Administrative Templates (.admx/.adml), or GPO deployment workflows. Modern Identity & Passwordless Auth: Familiarity with modern authentication protocols, FIDO2/WebAuthn, Passwordless logon architectures, or Microsoft Entra ID (Azure AD) hybrid join. Technical Leadership & Mentorship: Demonstrated technical leadership experience authoring Architectural Decision Records (ADRs), conducting structured code reviews, and mentoring fellow engineers. Why Cisco? At Cisco, we’re revolutionizing how data and infrastructure connect and protect organizations in the AI era – and beyond. We’ve been innovating fearlessly for 40 years to create solutions that power how humans and technology work together across the physical and digital worlds. These solutions provide customers with unparalleled security, visibility, and insights across the entire digital footprint. Fueled by the depth and breadth of our technology, we experiment and create meaningful solutions. Add to that our worldwide network of doers and experts, and you’ll see that the opportunities to grow and build are limitless. We work as a team, collaborating with empathy to make really big things happen on a global scale. Because our solutions are everywhere, our impact is everywhere. We are Cisco, and our power starts with you. Message to applicants applying to work in the U.S. and/or Canada: The starting salary range posted for this position is $139,300.00 to $203,600.00 and reflects the projected salary range for new hires in this position in U.S. and/or Canada locations, not including incentive compensation*, equity, or benefits. Individual pay is determined by the candidate's hiring location, market conditions, job-related skillset, experience, qualifications, education, certifications, and/or training. The full salary range for certain locations is listed below. For locations not listed below, the recruiter can share more details about compensation for the role in your location during the hiring process. U.S. employees are offered benefits, subject to Cisco’s plan eligibility rules, which include medical, dental and vision insurance, a 401(k) plan with a Cisco matching contribution, paid parental leave, short and long-term disability coverage, and basic life insurance. Please see the Cisco careers site to discover more benefits and perks. Employees may be eligible to receive grants of Cisco restricted stock units, which vest following continued employment with Cisco for defined periods of time. U.S. employees are eligible for paid time away as described below, subject to Cisco’s policies: 10 paid holidays per full calendar year, plus 1 floating holiday for non-exempt employees 1 paid day off for employee’s birthday, paid year-end holiday shutdown, and 4 paid days off for personal wellness determined by Cisco Non-exempt employees** receive 16 days of paid vacation time per full calendar year, accrued at rate of 4.92 hours per pay period for full-time employees Exempt employees participate in Cisco’s flexible vacation time off program, which has no defined limit on how much vacation time eligible employees may use (subject to availability and some business limitations) 80 hours of sick time off provided on hire date and each January 1st thereafter, and up to 80 hours of unused sick time carried forward from one calendar year to the next Additional paid time away may be requested to deal with critical or emergency issues for family members Optional 10 paid days per full calendar year to volunteer For non-sales roles, employees are also eligible to earn annual bonuses subject to Cisco’s policies. Employees on sales plans earn performance-based incentive pay on top of their base salary, which is split between quota and non-quota components, subject to the applicable Cisco plan. For quota-based incentive pay, Cisco typically pays as follows: .75% of incentive target for each 1% of revenue attainment up to 50% of quota; 1.5% of incentive target for each 1% of attainment between 50% and 75%; 1% of incentive target for each 1% of attainment between 75% and 100%; and Once performance exceeds 100% attainment, incentive rates are at or above 1% for each 1% of attainment with no cap on incentive compensation. For non-quota-based sales performance elements such as strategic sales objectives, Cisco may pay 0% up to 125% of target. Cisco sales plans do not have a minimum threshold of performance for sales incentive compensation to be paid. The applicable full salary ranges for this position, by specific state, are listed below: New York City Metro Area: $167,700.00 - $282,000.00 Non-Metro New York state & Washington state: $149,100.00 - $250,900.00 * For quota-based sales roles on Cisco’s sales plan, the ranges provided in this posting include base pay and sales target incentive compensation combined. ** Employees in Illinois, whether exempt o