Senior Security Tester (Penetration Testing)

Responsibilities

• Plan and execute safety-first penetration tests of OT/ICS environments (water and wastewater, energy, manufacturing, building systems), including passive asset discovery, Purdue-model segmentation testing and IT-to-OT pivot analysis
• Assess PLCs, RTUs, HMIs, SCADA servers, historians and engineering workstations across major vendors and SCADA platforms
• Test industrial protocols such as Modbus/TCP, DNP3, EtherNet/IP/CIP, S7comm, OPC UA, BACnet and IEC 60870-5-104/61850 for authentication, integrity and logic-manipulation weaknesses
• Build and use lab or digital-twin replicas to validate attack paths before touching production, and operate strictly within client-approved rules of engagement, change windows and safety constraints
• Map findings to ISA/IEC 62443, NIST SP 800-82 and MITRE ATT&CK for ICS, with remediation guidance that is realistic for plant operations
• Conduct vulnerability research on binaries, firmware, embedded/IoT devices, web applications and enterprise software using reverse engineering, source code review and fuzzing
• Write reliable proof-of-concept and weaponized exploits for memory corruption, logic flaws and authentication bypasses
• Deliver client engagements end to end and communicate findings clearly to both engineers and executives

Languages

Required

• Minimum 5 years of hands-on penetration testing and offensive security experience, including significant depth in at least two of: OT/ICS security, exploit development/vulnerability research, and AI/LLM security
• Hands-on experience testing LLM applications or agentic AI systems, with a working understanding of how models, retrieval, tools and permissions combine to create attack surface
• Proficiency in Python, C/C++, x86/x64 and ARM assembly, and Bash/PowerShell
• Familiarity with industry standards and frameworks including OWASP Top 10, CVE/CWE, OSSTMM, NIST, MITRE ATT&CK, ISA/IEC 62443 and MITRE ATLAS

Nice to have

• Rust or Go a plus
• Excellent written and spoken English, with the ability to convey complex technical concepts to technical and non-technical audiences

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