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Toss

Fintech super-app for payments and banking

Open Source Security Expert - Security Researcher

Offensive Security & TestingConfirmed live in the last 24 hours
Full-timeSeoul, South KoreaNo salary listedIn-person

About the Job

Requirements

  • Understand basic IT and security infrastructure environments.
  • Have development capabilities to develop and maintain in-house vulnerability assessment tools.
  • Be able to understand vulnerability assessment scripts and interpret assessments and results.
  • Have development experience with Django, Flask, Python, PowerShell, or Shell.
  • Understand microservices architecture and be able to assess REST API vulnerabilities.
  • Have communication skills to collaborate smoothly with diverse teams.

Responsibilities

  • Perform scheduled and ad hoc vulnerability assessments of Toss Bank infrastructure, including servers, networks, DBMS, and information security solutions.
  • Develop and maintain in-house diagnostic tools for vulnerability analysis and assessment of electronic financial infrastructure and major information and communications infrastructure.
  • Conduct vulnerability assessments from diverse perspectives, including web, mobile, and penetration testing.
  • Identify vulnerabilities at the source-code level and test whether they pose actual threats.
  • Work with stakeholders across teams to remediate discovered vulnerabilities.

Desired Qualifications

  • Understand the MITRE ATT&CK Framework and be able to conduct penetration testing in AD and Unix-like environments.
  • Understand native cloud environments, including Kubernetes and AWS.
  • Hold security-related certifications such as CISSP, Information Security Engineer, OSCP, or CREST.
  • Provide specific examples in the résumé of how and why AI tools were used in actual work or projects.
  • Describe work and projects in detail, including the context, process, and personal contributions, especially for vulnerability assessment and penetration testing cases.
  • Include examples of developing or improving vulnerability assessment scripts, challenging work, or direct development contributions.
  • Highlight experience solving complex problems in collaboration with diverse organizations.

About the Company

Toss

Fintech super-app for payments and banking

Toss is a South Korean financial services platform that started as a peer-to-peer money transfer service and has grown into a digital 'super app' for personal finance. Its products are accessed through one mobile interface that unifies bank accounts, credit cards, loans, investments, and other financial services, including its own Toss Bank and Toss Securities. It differentiates itself by offering a broad, integrated ecosystem—combining digital banking, asset management, and brokerage services under one roof and running its own banking and securities units. Its goal is to become the leading consumer finance platform in South Korea while expanding its user base globally.

Company size
1,001-5,000
Company stage
Series G
Total funding
$1.5B
Headquarters
Seoul, South Korea
Founded
2011

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