About this role

We are looking for a Staff/Principal Linux Infrastructure Engineer with deep expertise in Linux development, network driver creation, and performance optimization. In this hands-on, high-impact role, you will work directly in our TrustedServer Team to create and refine the core systems that drive ExpressVPN’s infrastructure. This role is ideal for a Linux expert with a record of notable contributions to the kernel or other relevant communities and a history of published research in the field.

What you’ll be Do:

• Develop, optimize, and maintain TrustedServer collaboratively with the team, ensuring this foundational technology continues to serve as the secure backbone of our global services.
• Lead advanced Linux development projects and maintain active contributions to the Linux and relevant communities, with a focus on optimizing network drivers and enhancing system performance.
• Create and maintain dedicated environments and labs to rigorously test and optimize system performance; analyze results and implement improvements that increase system speed, resilience, and scalability.
• Network Driver Development: Develop and refine custom network drivers tailored to the high-demand needs of our digital privacy and performance solutions.
• Write clear, comprehensive technical designs and test plans, ensuring complex infrastructure projects are heavily de-risked and cleanly architected.

What you’ll bring:

• Minimum of 7 years in Linux infrastructure and Linux development, with documented contributions to kernel or relevant repositories.
• Demonstrated experience in network driver development, performance testing frameworks, and significant contributions to the Linux and relevant communities.
• Deep expertise in C++/Rust programming, Linux kernel architecture, and network protocols.
• Advanced capabilities in performance tuning and development of testing frameworks.
• Strong analytical and problem-solving skills, with a hands-on, proactive approach to systems architecture and performance optimization.
• Degree in Computer Science, Computer Engineering, or a related field.

Nice to have:

• History of published research in systems performance, networking, or kernel architecture.
• Expertise in computer security, cryptography, secure coding practices, or public key infrastructure.
• Familiarity with modern VPN protocols, including WireGuard or our own open-source protocol, Lightway.

What we offer:

• Work with a modern tech stack in a strong engineering culture
• Influence on technical decisions and room to innovate
• Continuous learning opportunities and support for professional development
• A motivated, collaborative team with extensive experience
• A strategic role with real technical influence and ownership
• A modern engineering culture with CI/CD, observability, and a strong code review culture
• Purpose-driven work: we value security, quality, and depth over quick hacks

#LI-PS1

Senior Penetration Tester

If you’re passionate about security and privacy, and want to use your offensive security skills to help safeguard private, uncensored access to the internet for millions of customers, we’d love to speak with you. 

Who you are

You’re a natural at solving problems and identifying security weaknesses with deep expertise in application security and infrastructure, and you have experience working on teams that know how to remediate vulnerabilities you identified based on your recommendations. You aren’t afraid of change, and you ask the questions that need to be asked. A lack of clarity is something you can’t settle for, and you voice your concerns when the balance between effort and impact seems off. 

As someone with an offensive security mindset, you know there are always vulnerabilities waiting to be found, and you’re naturally collaborative to help find and address them. You’re always willing to hear ideas from your colleagues. Likewise, you're willing to share your own knowledge and mentor others. 

What you’ll do

As a senior individual contributor on our Offensive Security team, you’ll have a broad set of responsibilities including:

• Prepare and execute penetration testing projects of our assets, services and applications, either individually or as part of a team with members across various geographic locations such as Singapore, Hong Kong, London, Germany and Bucharest.
• We operate across a wide range of technologies, from client facing applications written in various languages for various platforms, to backend infrastructure and services, and router firmware. We provide an environment where you’ll be exposed to a wide range of technologies that form our tech stack.
• You’ll need a strong white-box testing methodology and the ability to identify bugs in source code to go along with good organization and communication skills when delivering penetration tests of our applications and services.
• Work closely with the engineering teams to provide expert guidance and advice on remediation of identified vulnerabilities
• Verify the existence of newly discovered vulnerabilities in our software stack, including triaging and verifying bugs from our bug bounty program and automated scanners, and develop novel attack vectors based on these 
• Manage and support penetration testing services performed by outside vendors, from project inception, scoping, completion of the assessment, and finally, working with engineering teams to have the identified issues remediated
• Bring creative solutions to fruition for solving some of the complex security challenges faced by our organization, and provide security reviews on technical design documents for our solutions. Identify areas where automated testing can be done, then develop, maintain and continuously improve tools to support these automated tests
• Mentor, guide and support other team members using your strong technical knowledge
• Identify inefficiencies in the team’s workflow, suggest solutions and drive them to completion

This role focuses strongly on your ability to perform penetration testing (with a specialization in either desktop and server applications, infrastructure, and mobile apps, depending on your experience). To be a good fit for this role, you should be able to read source code in various languages, identify security weaknesses and vulnerabilities in various platforms and efficiently deliver security assessment projects while mentoring junior team members. Networking knowledge is critical to succeed in this role.

What you’ll bring

• Identify vulnerabilities, misconfigurations and deviations from best practices within applications by means of manual source code review, static code analysis, and/or fuzzing using Burp Suite, AFL or similar tooling. We expect vulnerabilities to be identified and exploited up to the levels of OSCP, OSWE or OSED
• Analyze application binaries, shared libraries, and browser extensions through the use of debuggers and reverse engineering tools to understand the components of the application and assess their security posture, as well as how they interact with the underlying operating system
• Experience writing scripts in languages such as: Python, bash, or Golang to showcase your proof of concepts
• Experience writing automation workflows such as Github Actions
• Provide mentorship and guidance to other team members and share knowledge and findings with them
• Good knowledge of:
• TCP/IP, IDS/IPS, firewalls, WAF, and web content filtering
• Cryptography: PGP, SSH, PKI

How you’ll succeed

• Your capacity to consistently identify security vulnerabilities and provide sound remediation strategies alongside our engineering teams is key to success in this role
• You’ll be assigned as a security lead across a number of our projects, and will need to mentor more junior team members and help them grow their skillset
• Your ability to design technical solutions while staying ahead of industry trends will help drive continued security improvement, especially when supporting secure engineering designs

Finally, candidates with strong experience in manual source code review and vulnerability research, or a strong track record in this area (e.g. CTFs, bug bounty program activity, published CVEs) are preferred.

How we’ll support you

We believe in fostering an environment that empowers decision-making at all levels. Our culture is rooted in the inverted pyramid approach, where the engineers, who have a deep understanding of the product and the customers, are the ones who have the knowledge and the authority to make impactful decisions. 

• We prioritize treating every team member with respect and promote open and constructive feedback, ensuring a culture of trust and transparency
• We encourage learning through experimentation and provide a safe space for everyone to learn from their experiences
• Our managers are dedicated to facilitating career growth and creating an environment that attracts and supports talented engineers

#LI-PS1

About the Role

We are inviting expressions of interest from talented Rust Developers who are passionate about building high-performance, reliable, and scalable systems. This is not an immediate opening, but an opportunity to connect with engineers interested in future roles within our team.

As a Rust Developer, you will work on systems-level programming, backend services, and performance-critical applications. You’ll collaborate with cross-functional teams to design, develop, and optimize software that emphasizes safety, speed, and concurrency.

Key Responsibilities

• Design, develop, and maintain applications using Rust
• Write clean, efficient, and well-tested code
• Optimize systems for performance, scalability, and reliability
• Collaborate with product managers, designers, and other engineers
• Contribute to architecture decisions and technical direction
• Debug and resolve complex technical issues
• Stay up to date with developments in the Rust ecosystem