JavaScript Frontend Engineer (Web Security) - Lisbon based/hybrid

JavaScript Engineer - Web Browser Vulnerabilities

English Required / Based in Lisbon, Portugal / Hybrid

We are seeking a skilled JavaScript Engineer with a strong background in web technologies and cybersecurity to analyze, reverse engineer, and secure browser‑based applications, with a particular focus on web extensions. This role involves identifying malicious behaviors, conducting security assessments, and driving automation and process improvements within the security analysis lifecycle.

Key Responsibilities:

Analyze web extension code using static and dynamic analysis techniques to detect security violations and malicious behavior.

Perform JavaScript reverse engineering and debugging to understand complex or obfuscated codebases.

Identify, document, and report security vulnerabilities, including root cause analysis and recommended remediation steps.

Support the takedown and investigation of malicious browser extensions.

Conduct regular code reviews and provide constructive feedback aligned with secure coding best practices.

Analyze JavaScript code to identify malicious activities and, when necessary, reverse engineer the code.

Define and implement detection rules and security patterns to identify violations at scale.

Identify emerging threat patterns and share insights to enhance team detection capabilities.

Drive innovative ideas, recommend improvements, and help design and implement automation for existing processes.

Act as a technical consultant, providing guidance, clarification, and technical grooming to team members.

Collaborate effectively with cross‑functional teams and maintain clear technical documentation.

Contribute to continuous improvement of security workflows and tooling.

You are someone who brings:

Strong hands‑on experience with JavaScript, including advanced concepts such as closures, prototypes, variable scope, hoisting, callbacks, and OOP principles.

Required hands‑on experience with HTML and CSS.

Required knowledge of JSON, AJAX, and ES6/ES7 standards.

Good understanding of Node.js and Webpack.

Experience working with front‑end frameworks or libraries such as React, Angular, or jQuery.

Strong code analysis, debugging, and reverse engineering skills, particularly in JavaScript applications.

Ability to analyze JavaScript code and identify malicious activities effectively.

Good communication skills and the ability to work as a collaborative team player.

Added Advantages (Nice to Have):

Cybersecurity experience or strong security knowledge.

Familiarity with DAST and SAST methodologies.

Knowledge of cybersecurity open‑source tools such as Burp Suite, Nmap, or similar tools.

Understanding of obfuscation and de‑obfuscation techniques.

Experience writing technical and security assessment reports.

Additional employment information
Compensation information is accurate as of the date of this posting. Cognizant reserves the right to modify this information at any time, subject to applicable law.

Applicants may be required to attend interviews in person or by video conference. In addition, candidates may be required to present their current state or government issued ID during each interview.

Cognizant is an equal opportunity employer. Your application and candidacy will not be considered based on race, color, sex, religion, creed, sexual orientation, gender identity, national origin, disability, genetic information, pregnancy, veteran status or any other characteristic protected by federal, state or local laws.

Applicants for US based positions must be currently authorized to work for any employer in the United States. The company is unable to provide employment-based immigration sponsorship for US based positions.

If you have a disability that requires reasonable accommodation to search for a job opening or submit an application, please email CareersNA2@cognizant.com for roles based in the Americas or CareersIndia2@cognizant.com for roles based in India.

About Cognizant:
Cognizant (Nasdaq: CTSH) is an AI Builder and technology services provider, bridging the gap between AI investment and enterprise value by building full-stack AI solutions for our clients. Our deep industry, process and engineering expertise enables us to build an organization’s unique context into technology systems that amplify human potential, drive tangible outcomes and keep global enterprises ahead in a fast-changing world. See how at cognizant.ai or @cognizant.