Researcher Web Security

Who you are

• You know our adversaries. You understand bots, automation, and the tooling used to attack web applications at scale
• Deep web expertise. You know HTTP, TLS, browser internals, fingerprinting, CAPTCHAs, and the techniques used to evade them
• You love the hunt. You enjoy ethical hacking and reverse engineering, with an adversarial mindset that assumes every defense can be broken — and the creativity to prove it
• From research to detection. You translate what you learn about attackers into concrete signals defenders can use
• Mitigation without burning signals. You understand (or are curious to learn) how to act on attackers without burning the signals that make them detectable
• Disciplined in code. You script comfortably (e.g., Python, JavaScript) to build proofs-of-concept and tooling – and you write it cleanly, whether it's throwaway or meant to last
• Clear communicator. You explain complex attacker behavior to technical and non-technical audiences alike

What the job involves

• Cloudflare’s Engineering Team is home to some of the industry’s top engineers, dedicated to building and scaling innovative software that handles a huge proportion of the Internet
• Our Detection department sits at the heart of that mission: we identify automated, fraudulent, and malicious activity across the Internet and through our gateway
• We develop advanced detection systems and machine learning models that operate at scale, collaborating with Product and Engineering teams across the company to protect our customers and stay ahead of the constantly evolving threat landscape
• Study our adversaries deeply – reverse-engineer bot tools, automation frameworks, and fraud kits to understand how they work and how they evolve
• Play the cat-and-mouse game: probe our own detections like an attacker would, close the gaps, and stay a step ahead as adversaries adapt
• Track the bot and fraud ecosystem through tooling, marketplaces, and emerging techniques. Turn that intelligence into actionable detection signals
• Develop heuristics, signatures, and detection ideas grounded in real adversary behavior, partnering with Data Scientists and Engineers to bring them to life
• Design mitigations that neutralize attackers without tipping our hand; preserving our detection signals rather than teaching adversaries how to evade them
• Automate the work analysts do by hand by turning manual investigation and rule-writing into scalable, automated detection

The application process

• Please note that applicants who progress to the offer stage of the interview process may be asked to attend an in-person interview within one of the Cloudflare Offices or Cloudflare Hubs. More details about this will be available at that stage of the interview process

Benefits

• Competitive pay: We offer a competitive total rewards package, where every employee is an owner of our stock.
• Take-what-you-need vacation: We encourage employees to find a comfortable work-life balance by taking as many days off as they need while still being able to perform their jobs satisfactorily. (We really mean it!)
• Paid maternity & paternity leave: Our global parental leave policy allows up to sixteen paid weeks of bonding leave time for all qualifying new parents.
• Employee benefits: We offer a comprehensive benefits package including healthcare, life insurance, short- and long-term disability, pension plans in accordance with the market practice in our locations.
• Commuter program: We are flexible about where we work and value connecting at the office. Our commuter benefits program is in place to support team members' commute to work via public transportation without the extra cost burden.
• Wellbeing: Global offerings that provide mental health, childcare and family forming support to our employees across our offices.