Senior Offensive Security Engineer - Threat Modeling Lead

Cybersecurity Jobs; Alexandria (VA); On-site; USD 140,000 - 180,000; Full time

Job summary

Parry Labs, LLC is seeking a Senior Offensive Cybersecurity Engineer to lead authorized offensive security assessments and support testing across software, network interfaces, and distributed mission systems. The role is onsite in Alexandria, VA and focuses on building threat models, executing approved tests, and verifying remediation with reproducible evidence.

You will develop threat models, define rules of engagement, conduct penetration testing, and contribute to red-team and blue-team

Qualifications

• 7+ years of security engineering experience, including hands-on offensive testing or vulnerability research.
• Experience with authorized penetration testing, protocol analysis, fuzzing, and vulnerability assessment.
• Ability to review Rust or C/C++ and develop security test tooling in Python or a systems language.
• Experience analyzing Linux and network behavior, including TCP/IP, service configuration, and access controls.
• Experience producing reproducible findings, explaining security impact, and verifying remediation with engineering teams.
• U.S. citizenship and eligibility to obtain and maintain a U.S. government security clearance if required.

Responsibilities

• Develop threat models and security test plans mapped to system requirements and potential failure modes.
• Define authorized test scope, including rules of engagement and stop conditions with program stakeholders.
• Conduct penetration testing, protocol analysis, and vulnerability research within approved test environments.
• Build protocol and parser fuzzing tools.
• Add repeatable security checks to automated test workflows.
• Assess Linux services and network interfaces.
• Review Rust or C/C++ code for security weaknesses.
• Evaluate authentication, digital signatures, replay protection, and key handling with software/cryptographic engineers.
• Document findings with clear impact and remediation priorities.
• Retest fixes and preserve test evidence.
• Support red-team and blue-team exercises.
• Keep assessment signoff separated from implementation ownership.

Skills

Rust

C/C++

Python

Linux

TCP/IP

Education

Bachelor’s degree in cybersecurity, computer science, engineering, or related field

Tools

Cryptographic algorithms

post-quantum algorithms

Hardware security modules (HSMs)

key management

Job description

Parry Labs, LLC is seeking a Senior Offensive Cybersecurity Engineer to lead authorized offensive security assessments and support testing across software, network interfaces, and distributed mission systems. The role is onsite in Alexandria, VA and focuses on building threat models, executing approved tests, and verifying remediation with reproducible evidence.

You will develop threat models, define rules of engagement, conduct penetration testing, and contribute to red-team and blue-team