Information Systems Security Officer (ISSO)

The role

The Information Systems Security Officer will keep assigned systems secure, documented, and ready for customer or third-party review. You will work with system owners, IT, engineering, the SOC, and the Cybersecurity Lead to implement security requirements and support evidence.

What you will do

• Serve as the security point of contact for operations and keep teams informed on the current cyber posture.
• Work with the Cybersecurity team to assess requirements, risk findings, and due dates for contracts.
• Maintain the SSP, system inventory, policies, procedures, and supporting evidence for our CUI environment.
• Track NIST SP 800-171 and CMMC Level 2 implementation at the specific artifact level.
• Support ATO and RMF activities including creating and updating security documentation and writing POA&Ms with target completion dates.
• Validate evidence from our cybersecurity suite including CrowdStrike, Palo Alto, Tenable, and Jira.
• Lead vulnerability and configuration remediation with system owners.
• Lead security reviews on privileged accounts, terminated users, vulnerability results, and other security requests from the program.

Required qualifications

• Active TS/SCI clearance required
• US Citizenship required
• 3 or more years of experience as an ISSO, security compliance analyst, security engineer, system administrator with security responsibilities, or a similar role
• Strong working knowledge of NIST SP 800-171, CMMC Level 2, POA&M management, control evidence, and assessment preparation
• Experience maintaining an SSP or equivalent system security documentation and supporting formal security reviews
• Ability to understand and validate evidence from identity, cloud, endpoint, network, vulnerability, and logging platforms
• Strong follow-through across multiple teams and the ability to write security documentation that clearly reflects what is actually implemented

Nice to have

• Experience with ATO, RMF, NIST SP 800-53, SOC 2 Type II, ISO 27001, DFARS 252.204-7012, SPRS, STIGs, or classified system security
• Experience with Microsoft GCC High, CrowdStrike, Palo Alto, Tenable, AWS GovCloud, Entra ID, or similar enterprise security platforms
• Security+, CGRC, CISSP, or a comparable security certification
• Experience supporting aerospace, defense, national security, ATO, RMF, or other regulated technical environments

Benefits

• Equity in Apex
• 100% company-paid medical, dental, and vision for you and your dependents
• $100k life insurance at no cost
• Starting at 15 days vacation, growing to 20+ days annually
• 10 paid holidays
• 100% match on first 3% of 401(k), 50% on next 2%
• 8 weeks paid parental leave
• Childcare reimbursement up to $350/day for work-related travel
• Daily catered lunch and unlimited snacks
• Monthly office socials, pickleball tournaments, run club, and gatherings

Before you apply

• Active TS/SCI clearance required
• US Citizenship required
• Must qualify as a U.S. Person (U.S. citizen or national, lawful permanent resident, refugee, or individual granted asylum) or be able to obtain required export authorizations

About the company

Apex manufactures satellite buses at scale using a combination of software, vertical integration, and hardware. They are a fast-growing startup that has raised more than $500M in funding.