Senior Corporate Security Systems Engineer

Consequential Work. Dedicated People. About Onebrief

Onebrief builds collaboration and AI-powered workflow software for military planning and operational coordination.

Military planning is complex by nature, requiring teams to coordinate information, people, and decisions across systems and locations. Onebrief brings planning, collaboration, simulation, and AI into one connected environment, helping teams test strategies, adapt to changing conditions, and make decisions with greater clarity when the stakes are real.

We are a distributed team of builders from military, operational, and technology backgrounds who care deeply about improving how important work gets done. Some team members work remotely, while others work directly alongside customers in operational environments around the world.

Founded in 2019, Onebrief is backed by leading investors including General Catalyst, Battery Ventures, Insight Partners, Sapphire Ventures, and Human Capital. Valued at more than $2 billion, we continue to invest in product innovation, AI capabilities, and team growth.

Onebrief is growing, and the systems our employees rely on need to remain secure, resilient, and audit-ready as the company scales. We’re hiring a Corporate Systems Security Engineer to help build and operate the technical security foundations that protect our corporate environment.

This is a hands‑on security engineering role focused on owning and improving security across endpoints, identity, SaaS applications, browsers, Zero Trust infrastructure, and the broader corporate security stack. You’ll work at the intersection of security engineering, systems configuration, and automation—turning security requirements into technical controls that are measurable, repeatable, and difficult to drift away from.

A major focus of this role is reducing manual security operations. Rather than repeatedly collecting the same evidence or discovering configuration drift during an audit, we want to build systems that continuously enforce our security expectations and produce trustworthy evidence of their effectiveness.

You’ll work closely with Corporate IT, Security Operations, GRC, and application owners, but your mandate is security: understanding how systems can be abused or misconfigured, establishing secure defaults, and ensuring the controls protecting Onebrief continue to operate as intended.

You’ll help own and mature the security systems protecting Onebrief’s corporate environment.

Core responsibilities include:

• Own and improve enterprise security technologies across areas such as EDR, SIEM, MDM, Zero Trust, identity, browsers, and SaaS applications, including deployment, configuration, integrations, monitoring, and lifecycle management.
• Establish and enforce secure configuration baselines across corporate systems, continuously identifying configuration drift and building durable mechanisms to remediate it.
• Build API-driven, infrastructure-as-code, or workflow-based automation that connects security systems, eliminates repetitive security work, and makes control enforcement and evidence collection more reliable.
• Partner with Corporate IT and application owners to securely deploy and operate endpoints, applications, and SaaS platforms while maintaining appropriate security boundaries and technical controls.
• Improve security telemetry by integrating corporate systems and applications with centralized monitoring and ensuring the signals necessary to detect vulnerabilities, misconfigurations, and suspicious activity are available and actionable.
• Translate security and compliance requirements—including CMMC 2.0 and NIST-aligned controls—into practical technical implementations that can be continuously validated and supported with defensible evidence.

• 4+ years of hands‑on experience in security engineering, enterprise security, systems security, or a closely related technical role.
• Experience securing identity, SaaS, or Zero Trust environments and understanding how configuration decisions affect enterprise security.
• Experience building security automation using APIs, workflow automation platforms,…