Freelance Cybersecurity Developer (Client Hire)

Flexing It is a freelance consulting marketplace that connects freelancers and independent consultants with organisations seeking independent talent.

Flexing It has partnered with Our client, a global leader in energy management and automation, is seeking a proficient and creative Freelance CTF Challenge Developer. You will be responsible for designing, developing, and testing Capture the flag (CTF) challenges across various domains, including Industrial control systems (ICS), mobile, web, and thick client applications. The ideal candidate will have a strong background in cybersecurity, problem-solving skills, and a passion for creating engaging and educational challenges, with a focus on docker-based environments.

Responsibilities:

• Design and develop CTF challenges across various categories (e.g., ICS, mobile security, web exploitation, thick client security, etc.).
• Create simulations of servers for protocols such as Modbus, OPCUA, and DNP3 with limited functionalities, including broadcasting data objects of OPCUA service, pre-populated with predefined values within Modbus registers and coils, or data blocks for DNP3.
• Ensure challenges are realistic, educational, and engaging for participants.
• Utilize Docker to create isolated and reproducible challenge environments.
• Collaborate with the team to brainstorm and implement new challenge ideas.
• Test and validate challenges to ensure they function as intended.
• Provide detailed write-ups and solutions for each challenge.
• Update and maintain existing challenges based on feedback and new developments in the field.

Type of project: Deliverable-based

Nature of work: Full time (Remote)

Skills Required

• Proven experience in developing CTF challenges or participating in CTF competitions.
• Strong understanding of cybersecurity concepts and techniques across multiple domains (ICS, mobile, web, thick client).
• Proficiency in programming languages such as Python, C/C++, JavaScript, and knowledge of ICS-specific protocols (e.g., Modbus, OPCUA, DNP3).
• Experience with Docker and containerization.
• Familiarity with various cybersecurity tools and platforms.
• Excellent problem-solving skills and attention to detail.
• Ability to work independently and meet deadlines.
• Strong communication skills and ability to explain complex concepts clearly.

Preferred Qualifications:

• Experience with popular CTF platforms (e.g., CTFd, Hack The Box, TryHackMe).
• Knowledge of current cybersecurity trends and threats.
• Previous experience in a similar role or in cybersecurity training/education
• Strictly NO PLAGIARISM