Application Security Penetration Engineer

About Citi:

Citi, the leading global bank, has approximately 200 million customer accounts and does business in more than 160 countries and jurisdictions. Citi provides consumers, corporations, governments, and institutions with a broad range of financial products and services, including consumer banking and credit, corporate and investment banking, securities brokerage, transaction services, and wealth management.

As a bank with a brain and a soul, Citi creates economic value that is systemically responsible and in our clients’ best interests. As a financial institution that touches every region of the world and every sector that shapes your daily life, our Operations & Technology teams are charged with a mission that rivals any large tech company. Our technology solutions are the foundations of everything we do from keeping the bank safe, managing global resources, and providing the technical tools our workers need to be successful to designing our digital architecture and ensuring our platforms provide a first-class customer experience. We reimagine client and partner experiences to deliver excellence through secure, reliable, and efficient services.

Our commitment to diversity includes a workforce that represents the clients we serve from all walks of life, backgrounds, and origins. We foster an environment where the best people want to work. We value and demand respect for others, promote individuals based on merit, and ensure opportunities for personal development are widely available to all. Ideal candidates are innovators with well-rounded backgrounds who bring their authentic selves to work and complement our culture of delivering results with pride. If you are a problem solver who seeks passion in your work, come join us. We’ll enable growth and progress together.

The Role:

Citi is seeking an Application Security Penetration Tester to join its Offensive Security team, conducting deep-dive vulnerability assessments across web applications, mobile, thick clients, APIs, microservices, and emerging Generative AI/LLM implementations. This role is well-suited for either an experienced penetration tester looking to deepen their offensive security career or a software developer/engineer seeking to transition into cybersecurity. The analyst will manually identify, research, validate, and safely exploit known and zero-day vulnerabilities, then translate technical findings into clear risk guidance for developers, architects, and ML engineers. A key focus of the role is researching and applying LLM-based security testing techniques to uncover complex, non-obvious vulnerabilities that evade traditional automated and manual testing. The team supports pentesting of the firm's most critical applications while actively researching AI/LLM-driven automation to enhance pentest effectiveness.

Responsibilities

• Conduct manual vulnerability assessments and penetration testing across applications and/or infrastructure.
• Identify and validate potential security vulnerabilities across Citi applications, APIs, cloud-native services, and AI/ML architectures.
• Engineer functional proof-of-concept code and exploit scenarios to demonstrate the exploitability and tangible impact of identified security weaknesses.
• Research and use LLM-based security testing harnesses to uncover deeply embedded, non-obvious vulnerabilities.
• Identify multi-step business logic abuse chains, cryptographic flaws, and complex privilege escalation paths that evade manual and traditional automated testing.
• Accurately document discovered vulnerabilities, reproduction steps, attack chains, and risk ratings in standardized assessment reports.
• Report and articulate vulnerability assessment results to both technical and non-technical audiences.
• Clearly articulate vulnerabilities to application developers, system architects, and ML engineers. Ensure they understand the root causes and true business risks.
• Drive remediation by outlining a defense-in-depth approach to business stakeholders.
• Propose actionable mitigating controls, code-level remediation solutions, and AI safety guardrails to developers to fully close security gaps.
• Keep abreast of emerging offensive security techniques. Participate in threat modeling exercises and adversarial testing across both traditional and AI-driven technology stacks.
• Support pentesting engagements for the firm's critical, top-tier applications.
• Research new ways to automate pentest activities, including the use of AI/LLM tooling, to identify vulnerabilities more effectively.

Qualifications

• Minimum of 1-3 years of hands-on experience in penetration testing, application security assessment, or software development ideally in an enterprise environment.
• Hands-on experience with dynamic/proxy/network testing tools such as Burp Suite Proxy, AppScan, WebInspect, Nessus, NMAP, or OWASP ZAP.
• Hands-on experience with static analysis and software composition tools such as Checkmarx, BlackDuck, SonarQube, or Snyk.
• Exposure to AI security/adversarial testing tools such as Garak, PyRIT, Counterfit, or the Adversarial Robustness Toolbox (ART) is advantageous.
• Strong foundation in enterprise programming and scripting languages, including Python, Java, .NET/C#, C/C++, Ruby, and/or NodeJS.
• Familiarity with common web and application framework stacks, such as Spring, AngularJS, React, Struts, ASP.NET Core, or AI orchestration libraries.
• Deep knowledge of application architectures and enterprise infrastructure, including databases, middleware, web servers, and cloud computing (GCP, AWS, Azure) supporting microservices and containerized workloads.
• Deep knowledge of common industry security standards, including OWASP Top 10 and CWE/SANS Top 25.
• Working familiarity with emerging AI security standards, including OWASP Top 10 for LLMs, MITRE ATLAS, and NIST AI RMF.

Education

• Bachelor's degree in Computer Science, Cybersecurity, Information Technology, or a related discipline. Equivalent professional or hands-on experience may be considered in lieu of a degree.
• Must have or be willing to obtain industry-accredited security certifications such as OSCP, OSWE, GWAPT, GWEB, GPEN, GXPN, GMOB, CISSP, CEH, CompTIA Security+, or CySA+.

This job description provides a high-level review of the types of work performed. Other job-related duties may be assigned as required.

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In addition to salary, Citi’s offerings may also include, for eligible employees, discretionary and formulaic incentive and retention awards. Citi offers competitive employee benefits, including: medical, dental & vision coverage; 401(k); life, accident, and disability insurance; and wellness programs. Citi also offers paid time off packages, including planned time off (vacation), unplanned time off (sick leave), and paid holidays. For additional information regarding Citi employee benefits, please visit citibenefits.com. Available offerings may vary by jurisdiction, job level, and date of hire.

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We use automated processing, including artificial intelligence, for our legitimate business interests (or our reasonable and appropriate business purposes) to identify and align the candidate's skills and abilities with a specific job opening. Additionally, if you so choose, or consent, we can match your skills and abilities to other suitable roles at Citi.

Importantly, all our hiring processes and decisions, including determining your suitability for a role, are conducted, checked, and decided by individuals. Our automated processing and AI do not involve relying on automatic or autonomous decision-making. Please refer to any Jurisdictional Considerations, with specific provisions for your country (where relevant) for further details.

Illinois residents – AI Notice and Right

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Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.

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