Senior Penetration Tester

Big Stars is an end-to-end product engineering company based in Belgrade, Serbia. We create a space where people take initiative and go big. We focus on: - turning outdated systems into high-performing engines - creating clean products that users actually love - designing stable and secure environments - building complex tech products We invite a Senior Penetration Tester to join our team. ‼️ It's an office-based role – no remote or hybrid options. We provide relocation support if your current location is different. ✅ Responsibilities: ✔️ Lead end-to-end penetration testing engagements across web applications, APIs, mobile, internal and external networks and cloud (primarily AWS). ✔️ Run red-team and assumed-breach operations - initial access, privilege escalation, lateral movement, persistence, exfiltration - including against fraud and detection stacks. ✔️ Perform security reviews of cloud-native services, Kubernetes workloads, CI/CD pipelines, and microservices. ✔️ Discover and exploit vulnerabilities across real-money flows - payments, deposits and withdrawals, wallets, KYC / AML, bonus systems, and affiliate tracking. ✔️ Partner with product, engineering, AppSec, payments, and fraud teams to translate findings into concrete fixes and durable controls. ✔️ Develop custom tooling, scripts, and methodology where no out-of-the-box approach exists. ✔️ Build and validate declarative threat models and contribute to "secure by design" practice. ✔️ Mentor mid and junior testers, review their engagement plans and reports. ✔️ Track new CVEs, TTPs, MITRE ATT&CK updates, and regulator advisories - translate them into concrete changes here. ✔️ Support pre-sales scoping, effort estimation, and pre-certification engagements for new products and jurisdictions. ✔️ Serve as a trusted offensive-security advisor to product, engineering, and compliance teams. ✅ Requirements: ✔️ Minimum 4 years of hands-on penetration testing or offensive-security experience. ✔️ Proven track record across at least three of: web / API, internal, external network, cloud (AWS / GCP), mobile (iOS / Android). ✔️ OSCP or an equivalent in-the-box certification. ✔️ Strong working knowledge of SAST/SCA/DAST tooling, AWS/GCP, MITRE ATT&CK, OWASP ASVS / WSTG, PTES. ✔️ Understanding of the data flow, MVC model. ✔️ Understanding of supply chain attacks. ✔️ Good reporting skills. ✔️ Comfortable scripting in Python plus Bash. ✔️ Knowledge at least one of major cloud provider's IAM model. ✔️ Experience pentesting cloud-native systems and Kubernetes environments, plus the CI/CD pipelines around them (GitLab, GitHub Actions, Jenkins) and IaC (Terraform, Helm, CloudFormation). ✔️ Strong written and verbal communication in English . ✔️ Experience balancing security and business demands under release pressure. ✔️ Familiarity with industry regulations, frameworks, and practices: PCI DSS, ISO 27001, NIST, GDPR . ✅ PREFERRED QUALIFICATIONS: ✔️ One of offensive-security certifications: OSWE, OSEP, OSED, CRTO, BSCP, ARTE, GRTE . ✔️ In-depth experience architecting secure services on Kubernetes and AWS. ✔️ Prior iGaming, fintech, or payments domain experience. ✔️ Public CVEs, advisories, write-ups, conference talks. ✔️ HTB Pro Lab completions, real CTF placements. ✔️ Open-source contributions to offensive or defensive tooling. ✅ We offer excellent benefits, including but not limited to: 🏝 24 vacation days annually. 🤒 6 sick days without a medical certificate. 🏥 Premium Health Insurance (coverage up to 5,000 EUR annually). 🎉 Special occasion gifts: birthday, wedding, newborn. 📚 Learning & Development budget (for conferences, courses and certifications). 🌍 Corporate events: international parties, team buildings, activities. 📈 Career growth opportunities in a fast-growing company. ✈️ Relocation package for international candidates. 🏋️ Sports package (FitPass membership). 🗣️ Language classes: Serbian & English (company-covered). Big Stars paves the way to excellence by helping people grow.