Senior Staff Engineer

Role Description

As a Senior Low-Level Software Engineer at Cortex, you will be a technical authority and an escalation point locally for the Cortex Cloud Windows endpoint agent. You will own the kernel- and user-mode components that deliver detection, prevention, and visibility across millions of Windows endpoints, and the deep-system engineering required to keep those components stable, performant, secure, and compatible across a highly fragmented OS and third-party ecosystem. This is a high-impact individual-contributor role. You will be responsible to handle critical field issues escalations from Technical Support teams, root cause analysis, interfacing with the support teams and occasionally with customers during live debug sessions. You will be part of a senior team responsible for the architectural integrity, runtime stability, and forensic debuggability of agent code paths that execute alongside the NT kernel and core OS subsystems - spanning multiple production kernel drivers, user-mode service, injection/hooking engine, and EDR module. Because our agent runs at the highest privilege levels on customer production machines, every defect is potentially a system-wide outage, a blue screen across a fleet, or a security exposure, so engineering rigor, defensive design, and disciplined debugging are non-negotiable.

Key Responsibilities

• Serve as the local technical authority for critical field issues, providing a direct link between customer-facing support teams and the core R&D organization.
• Lead technical investigations for the highest-severity customer escalations, facilitating live debugging sessions in production-adjacent environments to expedite resolution.
• Synthesize complex technical findings into concise, compile RCA reports, actionable reports for Global Support, Product Management, and engineering leadership to inform prioritization, customer communication, and roadmap decisions.
• Design, implement, and maintain user-mode agent components and in some cases Windows kernel drivers.
• Work across the native interop boundary - low-level user-mode code injection, API hooking, NT Native API, etc.
• Drive defensive engineering practices so that an agent fault never bricks a customer endpoint - input validation at trust boundaries, graceful degradation, fail-open vs. fail-closed decisions, watchdog/self-healing mechanisms, etc.
• Identify and remediate functional regressions, performance regressions, and system instability (including bugchecks/BSODs) caused by interactions between the Cortex agent and third-party security software, competing EDR/AV products, virtualization layers, malicious drivers, and low-level system utilities.
• Use fleet-scale telemetry - crash signatures, BSOD bugcheck codes, content-update regression signals, and driver-conflict indicators - to detect emerging stability issues early, triage and root-cause across kernel, user mode, and third-party boundaries.
• Partner with the release and content pipelines (GitLab) to gate risky changes and to ensure new agent versions and content/policy updates do not introduce regressions on the diverse hardware and software configurations in the field.
• Own identification and resolution of kernel-mode and user-mode failures that threaten system stability or agent integrity. Perform deep analysis of complete, kernel, and minidumps using WinDbg to isolate race conditions, memory corruption, use-after-free, deadlocks, lock-order inversions, and pool corruption in production environments.
• Diagnose high-latency operations, CPU contention, and resource exhaustion by analyzing system-wide traces with ETW, Windows Performance Recorder & Analyzer (WPR/WPA), Performance Monitor, Process Monitor, and Process Explorer; drive the resulting optimizations into shipping code and verify the win with telemetry.
• Use and help refine internal AI agents via CLI and IDE integrations to accelerate low-level code analysis, automate patch and test generation (GoogleTest-based native unit tests), and speed up the parsing of complex diagnostic telemetry (crash dumps, ETW traces, driver logs, WPP/TMF traces).

Qualifications

• Bachelor's degree with 5 years of experience or Master's degree with 3 years of experience or new grad with PhD.
• Systems Programming Mastery - Deep, hands-on proficiency in C for both kernel- and user-mode Windows development, plus working command of modern C++ (C++17/20) for library integration. Strong command of undefined behavior, memory models, custom allocators/CRT constraints, and the discipline required for code that cannot crash. Comfort reading/writing x86/x64 assembly (MASM) is strongly desired.
• Windows Internals - Strong understanding of the NT kernel, I/O manager, object manager, memory manager, IRQL and synchronization primitives, PnP/Power, boot and driver load order, and the Windows security model (tokens, ACLs, integrity levels, Protected Process Light). Familiarity with the NT Native API and ALPC/named-pipe/filter-port IPC.
• Advanced Debugging - Fluency with WinDbg, including kernel debugging and !analyze workflows, for analyzing complete, kernel, and minidumps; ability to root-cause defects from a crash dump alone when live repro is impossible.
• Performance Engineering - Experience profiling and optimizing systems software using ETW, WPR/WPA, Performance Monitor, Process Monitor, and Process Explorer to eliminate latency, contention, and resource-exhaustion issues in hot paths.
• Systemic Problem Solving - Track record of root-causing complex failures that span kernel, user mode, and third-party software interactions in production environments at scale.
• Influence & Communication - Exceptional ability to communicate complex low-level technical concepts to both highly technical peers and non-technical stakeholders, including written incident analyses, post-mortems, and architectural proposals.

Preferred Qualifications

• Endpoint Security Background - Prior experience building EDR, AV, DLP, or other endpoint security agents, including anti-tamper, self-protection, and code-integrity constraints, and an understanding of the adversarial pressure such agents operate under.
• Security & Detection Libraries - Familiarity with YARA, high-performance regex engines (Hyperscan, RE2), OpenSSL, and serialization/RPC stacks (Protobuf/nanopb, gRPC).
• Rust in Systems Code - Hands-on experience introducing Rust into existing C/C++ codebases, including FFI boundaries, build integration, and safety/ownership patterns relevant to long-running, high-privilege agent processes.
• Driver Development - Experience building and shipping Windows kernel drivers is an advantage and not required, practical exposure to at least one of: WDK (WDM/KMDF), File System Minifilters, WFP callouts, ELAM, or kernel-mode callback frameworks. Experience building across x64/x86/ARM64 is a plus.
• Fleet-Scale Telemetry & Reliability - Experience using large-scale telemetry and crash analytics to drive reliability, detect regressions, and prioritize fixes by real-world customer impact.
• Reverse Engineering & Diagnostics - Working knowledge of IDA Pro, Ghidra, or x64dbg, and/or disassembly frameworks (BeaEngine, Capstone, Zydis), for analyzing third-party drivers, compatibility issues, or malware-driven crashes.
• Adjacent Platforms - Exposure to low-level development on macOS (Endpoint Security framework, kexts/system extensions) or Linux (eBPF, LSM, kernel modules) is a plus, as the agent shares a cross-platform core (CPA) across Windows/Linux/macOS.
• Modern Tooling - Experience leveraging AI-assisted development tools (e.g., Gemini, Claude) to optimize the SDLC and automate complex debugging, code-review, and test-generation tasks for systems software.