Principal Cybersecurity Network Engineer - Critical Infrastructure

Job Description:

This position requires office presence of a minimum of 5 days per week and is only located in the location(s) posted. No relocation is offered.

Join AT&T and reimagine the communications and technologies that connect the world. Our Chief Security Office ensures that our assets are safeguarded through truthful transparency, enforce accountability and master cybersecurity to stay ahead of threats. Bring your bold ideas and fearless risk-taking to redefine connectivity and transform how the world shares stories and experiences that matter. When you step into a career with AT&T, you won’t just imagine the future-you’ll create it.

Join our company as a Principal Network Security Engineer and lead offensive security initiatives that rigorously test and improve the resilience of our core telecom network and infrastructure. You will be at the forefront of simulating advanced adversaries, identifying critical vulnerabilities, and influencing security strategies to defend one of the world’s largest telecommunications networks.

Key Responsibilities:

• Perform penetration testing and pressure testing on pre-production network infrastructure and document remediation required for production deployment
• Research adversarial tactics, techniques and procedures relevant to critical infrastructure in use or in consideration for use
• Lead and design adversary simulation exercises and targeted penetration testing to certify pre-production network infrastructure across multi-vendor network environments and telecom critical infrastructure
• Identify, exploit, and weaponize network vulnerabilities such as BGP hijacking, ACL bypasses, segmentation flaws, and misconfigurations in routers, firewalls, and network segmentation for pre-production environments.
• Leverage Python scripting to automate ongoing security testing on various network elements
• Mentor and develop offensive security mindsets with the current Network Security Blue Team members
• Collaborate closely with blue teams, SOC, and incident response teams to provide actionable intelligence, improve detection capabilities, and refine defense mechanisms.
• Engage with internal stakeholders and executive leadership to communicate findings, risks, and strategic recommendations based on Network Element vulnerability assessments.

Qualifications:

Education:

• Bachelor’s degree or higher in Computer Science, Cybersecurity, Information Technology, Engineering, or related field. Advanced degrees or certifications such as OSCP, OSCE, GIAC GPEN, or similar are highly desirable.

Experience:

• 8+ years of network security experience and 3+ years of offensive security and penetration testing within large-scale ISP, telecom, or enterprise environments.
• Extensive hands-on expertise exploiting network infrastructure vulnerabilities, including routing protocols (BGP, OSPF, MPLS), network device firmware, and network security controls.
• Knowledge of and continued research of the most significant Advanced Persistent Threats (APTs) for telecom’s critical infrastructure
• Hands-on experience with various offensive security tools as well as network traffic analysis
• Strong Linux proficiency for offensive security operations.
• Experience with automating API calls for security data collection and automation
• Familiarity with scripting and automation using Python
• Proven ability to conduct threat modeling and emulate advanced threat actor tactics, techniques, and procedures (TTPs).
• Experience collaborating with blue teams and SOCs to improve detection, response, and mitigation strategies.
• Extensive experience with multi-vendor network platforms from an offensive security perspective, including Cisco, Juniper, Arista, Palo Alto, Fortinet, and UfiSpace.

Desired Skills & Attributes:

• Exceptional adversarial mindset with creativity and persistence to uncover complex security weaknesses.
• Strategic thinker who can align offensive security efforts with organizational risk management and business goals.
• Ability to manage multiple complex engagements simultaneously while maintaining meticulous attention to detail.
• Collaborative leader who fosters knowledge sharing and continuous improvement within teams.
• Strong ethical standards and commitment to responsible disclosure and security best practices.

Why Join Us?

• Play a critical role in defending a global telecommunications network by thinking like an attacker.
• Work with cutting-edge offensive security tools, techniques, and technologies in a collaborative and innovative environment.
• Influence security strategy at the highest levels and contribute to industry-leading standard