Endpoint Security Engineer III - Nessus
CACI International
St. Louis, MO · Posted July 31, 2026
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About the job
Job Title: Endpoint Security Engineer III - Nessus
Job Category: Information Technology
Time Type: Full time
Minimum Clearance Required to Start: TS/SCI
Employee Type: Regular
Percentage of Travel Required: Up to 10%
Type of Travel: Local
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The Opportunity: CACI has an exciting opportunity for a Senior Endpoint Security Engineer to join our Transport & Cybersecurity Services (TCS) team in either Springfield, VA or St. Louis, MO. Our Endpoint Security team is rapidly growing! This is one of several New positions that we have added to the TCS program. This is an exceptional opportunity for a TS/SCI cleared professional to join an incredibly talented team, work with cutting edge technologies, and propel your career within the Cyber realm!
TCS is a long-term, CACI Prime contract with the National Geospatial-Intelligence Agency (NGA) in support of the customer’s GEOINT mission. The Endpoint Security Engineer will support our Intelligence Community customer’s various endpoint security platforms. Positions on TCS require a TS/SCI clearance to be eligible for hire; with the ability to successfully pass a Government polygraph as a post-hire requirement.
Position Overview: We are seeking a highly skilled Tenable product Administrator with hands-on experience in Linux platforms to join our team. The ideal candidate will be responsible for managing and administering our Tenable Suite environment, as well as configuring and maintaining them on Linux systems. This role requires a deep understanding of vulnerability management, security protocols, and the Tenable product suite, with a strong focus on Linux-based installations.
Responsibilities: • Install, configure, and maintain the Tenable Security Center, Tenable Nessus Scanners, and Tenable Nessus Managers on Linux platforms. • Perform regular vulnerability scans and assessments across the organization's network using Tenable products • Analyze scan results and prioritize vulnerabilities based on severity and impact. • Collaborate with IT and security teams to remediate identified vulnerabilities. • Generate and distribute vulnerability reports to stakeholders. • Monitor security alerts and respond to incidents in a timely manner. • Stay updated on the latest security threats and vulnerabilities. • Provide training and support to users on the Tenable Security Center, Tenable Nessus Scanners, and Tenable Nessus Managers on Linux • Ensure the optimal performance and security of the Tenable environment on Linux platforms • Configure and install various security products utilizing Linux OS.
Qualifications: Required: • TS/SCI clearance (current). As a post-hire requirement, selected candidate must be able to successfully pass and maintain a Government polygraph. • DoD 8570 IAT Level II certified (current) • Must obtain a CSSP Infrastructure Support certification within 6 months of hire date • Bachelor's degree (Engineering, Computer Science or related field) and ten (10) years of technical experience in Cyber Security. Additional experience may be considered in lieu of a degree. • Working knowledge of maintaining Enterprise Cyber Security Engineering requirements utilizing all or some of the following tools: Tenable Suite that include Security Center, Nessus Scanners, Nessus Manager with hands-on administrator experience • Strong working knowledge of Linux operating systems, including installation, configuration, and maintenance • Experience with large-scale enterprise/global networks in a high-paced, diverse environment • Understanding of and experience with the DoD Architecture Framework and other key DoD network architecture and strategic planning instructions • Experience in providing status reports and products to senior management and customers • Experience with plans, designs, and evaluations of security systems and architectures
Desired: • CSSP Infrastructure Support certification • Any Linux related certifications • Familiarity with scripting languages (e.g., Python, PowerShell) for automation tasks
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What You Can Expect:
A culture of integrity.
At CACI, we place character and innovation at the center of everything we do. As a valued team member, you’ll be part of a high-performing group dedicated to our customer’s missions and driven by a higher purpose – to ensure the safety of our nation.
An environment of trust.
CACI values the unique contributions that every employee brings to our company and our customers - every day. You’ll have the autonomy to take the time you need through a unique flexible time off benefit and have access to robust learning resources to make your ambitions a reality.
A focus on continuous growth.
Together, we will advance our nation's most critical missions, build on our lengthy track record of business success, and find opportunities to break new ground — in your career and in our legacy.
Pay Range :
There are a host of factors that can influence final salary including, but not limited to, geographic location, Federal Government contract labor categories and contract wage rates, relevant prior work experience, specific skills and competencies, education, and certifications. Our employees value the flexibility at CACI that allows them to balance quality work and their personal lives. We offer competitive compensation, benefits and learning and development opportunities. Our broad and competitive mix of benefits options is designed to support and protect employees and their families. At CACI, you will receive comprehensive benefits such as; healthcare, wellness, financial, retirement, family support, continuing education, and time off benefits.
The proposed salary range for this position is: $75,200-$158,100
CACI is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, pregnancy, sexual orientation, age, national origin, disability, status as a protected veteran, or any other protected characteristic.