What we do:
Halcyon is the industry’s first dedicated, adaptive security platform that combines multiple proprietary advanced prevention engines along with AI models focused specifically on stopping ransomware.

Who we are:
Halcyon was formed in 2021 by a team of cyber industry veterans after battling the scourge of ransomware (and advanced threats) for years at some of the largest global security vendors. Comprised of leaders from Cylance (now Blackberry), Accuvant (now Optiv), Fireye and ISS X-Force (now IBM), Halcyon is focused on building products and solutions for mid-market and enterprise customers.

As a remote-native, completely distributed global team, we recognize great talent can exist anywhere. We invite you to apply to a job you’re interested in and we'll work a plan to meet your needs.

The Role:

Halcyon is building the most resilient anti-ransomware platform on the market, and we need a Windows kernel expert at the forefront of our agent development. As a Principal Kernel Engineer, you will play a key role in the design and evolution of our Windows kernel components that prevent, detect, and respond to ransomware.

This role demands deep, exclusive experience with Windows OS internals and the ability to ship robust, secure, high-performance drivers in security-critical environments. You’ll work closely with senior engineers, product teams, and security experts to help evolve our kernel architecture, mentor other developers, and ensure our platform remains reliable and resilient.

Responsibilities:

• Apply deep Windows kernel expertise to develop and optimize kernel-mode components that power Halcyon’s ransomware prevention and detection capabilities.

• Contribute to the design and implementation of secure, high-performance Windows drivers (e.g., file system mini-filters, network callout drivers, process/thread monitoring).

• Investigate, debug, and resolve complex kernel-level issues — from race conditions to memory corruption — using WinDbg, crash dump analysis, and advanced debugging techniques.

• Help set technical direction for kernel development across the Windows agent, influencing architecture and performance trade-offs.

• Mentor and guide other engineers in kernel-mode development best practices and secure coding patterns.

Skills and Qualifications:

• 15+ years of exclusive, professional Windows kernel development — deep understanding of NT internals, OS architecture, and low-level subsystems.

• Proven track record of shipping multiple production-quality Windows drivers (file system, networking, or security-related) in commercial products.

• Mastery of C++ in kernel-mode and user-mode, including multithreading, synchronization primitives, IRQL management, and lock-free programming.

• Expert-level debugging skills — WinDbg, KD, crash dump analysis, race condition resolution.

• Strong knowledge of Win32 APIs, kernel security boundaries, and performance tuning at the OS level.

• Experience designing for stability, security, and performance.

• Exceptional communication skills and ability to collaborate across engineering and product teams.

Bonus skills and Qualifications:

• Experience with Rust in systems programming, or a strong desire and capacity to learn quickly.

• Familiarity with Portable Executable (PE) format and reverse engineering tools.

• Hands-on experience with Windows Mini-Filter drivers, Windows Filter Platform (WFP), or kernel-based process protection mechanisms.

• Exposure to Rust/C++ interoperability in production systems.

• Background in endpoint security, EDR, or other OS-level security products.

Benefits:

Halcyon offers the following benefits to eligible employees:

• Comprehensive healthcare (medical, dental, and vision) with premiums paid in full for employees and dependents.

• 401k plan with a generous employer contribution.

• Short and long-term disability coverage, basic life and AD&D insurance plans.

• Medical and dependent care FSA options.

• Flexible PTO policy.

• Parental leave.

• Generous equity offering.

The Company reserves the right to modify or change these benefits programs at any time, with or without notice.​

Base Salary Range: $235,000 - $275,000

Bonus Target: 10%

In accordance with applicable state and federal laws, the range provided is Halcyon’s reasonable estimate of the base compensation for this role. The actual amount may differ based on non-discriminatory factors such as experience, knowledge, skills, abilities, and location. Base pay is one part of the total package that is provided to compensate and recognize employees for their work, and this role may be eligible for additional discretionary bonuses/incentives, and equity in the Company.

We understand it takes a diverse team of highly intelligent, passionate, curious, and creative people to develop the exceptional product we are building. Our dynamic team has incredible perspectives to share, just as we know you do, and we take great pride in being an equal opportunity employer.