Senior Low-Level Security Engineer – macOS (C/C++)

About the Company

Our client is an early-stage cybersecurity startup building foundational endpoint security technology for Windows, Linux, and macOS.Their work lives deep in the operating system: processes, memory, kernel boundaries, and attacker tradeoffs. We focus on real threats, real exploits, and defensive systems that must hold up against skilled adversaries — not academic exercises.

About the Role

We are looking for a Senior Low-Level Security Engineer with strong C/C++ systems-programming skills and a deep understanding of macOS internals and security.
This is a highly hands-on role. You will design and implement low-level components for our endpoint security platform, analyze vulnerabilities and attack techniques, and build robust defensive mechanisms with a primary focus on macOS.
You will work at the intersection of systems programming, vulnerability research, and security engineering, with direct influence on our product architecture and security strategy.

What You'll Do

• Design and implement low-level macOS components using modern C++(C++17/20).
• Develop security-sensitive code that interacts with operating-system and kernel-level primitives.
• Work deeply with macOS internals, including processes, threads, memory management, filesystems, IPC, and networking.
• Build and maintain integrations with the Endpoint Security Framework (ESF), System Extensions, and Network Extensions.
• Analyze real-world attacker techniques, exploits, and vulnerabilities.
• Design and implement defensive mechanisms, hardening strategies, and exploit mitigations.
• Perform reverse engineering and low-level analysis of binaries and system behavior.
• Reason about performance, correctness, and safety in multithreaded environments.
• Optimize endpoint components for performance, memory usage, stability, and reliability.
• Participate in architecture decisions, code reviews, and security-design discussions.
• Collaborate closely with detection, security research, product, and engineering teams.
• Diagnose and resolve complex, low-level production issues.

Requirements

• 5+ years of hands-on experience in low-level systems programming or security engineering.
• Strong expertise in C and C++ within security- or systems-oriented, performance-critical environments.
• Deep understanding of macOS internals and its security model.
• Strong hands-on experience with:
  o Endpoint Security Framework (ESF)
  o System Extensions
  o Network Extensions
• Strong knowledge of multithreading, synchronization, and concurrency.
• Experience with reverse engineering and low-level system analysis.
• Assembly-level understanding of x86, ARM, or similar architectures.
• Strong understanding of security vulnerabilities, exploit techniques, and mitigations, including ASLR, DEP, sandboxing, and related protections.
• Experience analyzing binaries, source code, and runtime behavior to identify security flaws.
• Strong debugging and problem-solving skills in complex technical environments.
• Ability to evaluate and communicate complex technical trade-offs clearly.
• Strong written and spoken English.
• Ability to work independently and collaborate effectively in a remote environment.

Nice to Have

• Familiarity with Windows or Linux internals.
• Kernel-level development or exploit-research experience.
• Experience with vulnerability research, fuzzing, or static and dynamic
  analysis.
• Malware analysis or digital forensics and incident response experience.
• Experience with firmware, hypervisors, or virtualization security.
• Offensive-security or advanced penetration-testing experience.
• Experience building EDR/XDR platforms or endpoint agents.
• Knowledge of macOS system security and platform-integrity mechanisms, including System Integrity Protection (SIP), Transparency, Consent, and Control (TCC), sandboxing, and code signing.
• Familiarity with Grand Central Dispatch (GCD).
• Experience working in an early-stage or deep-tech startup.

Why Join Us

• Real Security: Work on defenses against real attackers and real exploits.
• Technical Depth: Solve meaningful challenges involving macOS internals and low-level engineering.
• Impact: Build core components of a foundational cybersecurity product.
• Hands-On Role: Work directly with complex systems and low-level technologies.
• Growth: Develop into a senior technical authority in low-level security engineering.