Security Engineer I, Application Security

About this role

Location: Remote, United States
About Trail of Bits

Founded in 2012 by 3 expert hackers with no investment capital, Trail of Bits is the premier place for security experts to boldly advance security and address technology's newest and most challenging risks. It has helped secure some of the world's most targeted organizations and devices. Our combination of novel research with practical solutions reduces the security risks that our clients face from emerging technologies. Our work helps drive the security industry and the public understanding of the technology underlying our world.
Cybersecurity preparedness is a moving target. Companies like ours are the tip of the spear in the fight against attackers. Our research-based and custom-engineering approach ensures that our client's capabilities are at the forefront of what's available. For companies and technologies that live and die by their security, a proactive, tailored approach is required to keep one step ahead of attackers.
Democratizing security information is essential. As part of our business, we provide ongoing informational support through blogs, whitepapers, newsletters, meetups, and open-source tools. The more the community understands security, the more they'll understand why a company like ours is so unique and valuable.
The Role
Trail of Bits seeks a Security Engineer I for our Application Security practice. You will contribute to security assessments of client software, partner with more experienced engineers, identify vulnerabilities across the application and system levels, and own clearly scoped pieces of client engagements. You will drive your own vulnerability analysis, develop tools alongside the team, and help clients understand and fix the issues you find.
This role bridges vulnerability research and applied security. Your work will be hands-on: analyzing complex code, building custom tooling, conducting threat modeling, and owning your findings through client delivery. It is distinct from roles centered on security operations, SOC work, GRC, compliance, policy, audit, or general security administration. Candidates from broader or adjacent security backgrounds should be prepared to talk through relevant hands-on, code-level security work they have personally completed.
Security Engineer I is an early-career role, but it is not a training role for someone new to software or security. Relevant experience may come from professional work, internships, advanced coursework, independent research, open-source contributions, CTFs, or substantial personal or academic projects. Regardless of where you gained the experience, you should be able to talk through code-level security work you performed, how you approached the problem, and the conclusions you reached. You will receive direction and review from a project lead while independently completing well-scoped technical work.
What You'll Achieve

• Security Assessment Ownership: Lead the review of a specific component, module, or system within a larger client engagement. Trace root causes and own your analysis from discovery through client delivery.

• Vulnerability Discovery and Analysis: Find and validate vulnerabilities in application code and systems, explain exploitation paths, assess impact, and develop proof-of-concept code when appropriate.

• Custom Security Tooling: Design and build security-testing tools and automation for vulnerability detection and deeper analysis.

• Architecture and Threat Modeling: Review software architectures, identify attack surfaces, data flows, trust and privilege boundaries, and recommend concrete mitigations.

• Client Communication: Translate technical findings into clear, actionable recommendations for engineering teams and explain the evidence behind your conclusions.

• Research and Innovation: Contribute to security research, open-source tools, internal knowledge sharing, and technical documentation.

What You'll Bring
The following are requirements for this role:

• At least 1 year of combined relevant experience in application security, vulnerability research, security-focused software engineering, or a closely related area. This experience may come from employment, internships, advanced coursework, independent research, open-source contributions, CTFs, or substantial personal or academic projects.

• Demonstrable vulnerability-discovery capability. You can talk through a vulnerability or security weakness you personally found or validated, including how you identified it, established its impact, and reached your conclusion. Evidence may come from professional work, coursework, projects, CTFs, CVEs, bug bounties, responsible disclosure, open source, or comparable research.

• Strong code-analysis skills. You can read unfamiliar code, trace execution and data flow, identify logic or implementation flaws, and distinguish a tool signal from a validated vulnerability.

• Hands-on coding proficiency in at least two relevant languages, such as Rust, Go, C, C++, Python, JavaScript, TypeScript, or similar languages used in security analysis and tool development.

• Working knowledge of memory-corruption vulnerabilities and common mitigations, such as buffer overflows, use-after-free, stack cookies, ASLR, NX/DEP, CFI, or MTE, including the ability to reason about exploit primitives at an appropriate early-career level.

• Familiarity with operating-system concepts, IPC, privilege boundaries, and the ways applications interact with system internals.

• Ability to independently investigate a well-scoped problem, debug issues, document evidence, ask focused questions when blocked, and deliver work with review from a project lead.

• Clear written and verbal communication, including the ability to explain technical findings and remediation guidance to software engineers and work productively on a distributed team.

Preferred Qualifications
These are not day-one requirements, but areas where the role can grow.

• Active or recent CTF…