Cyber Network Defense Analyst

Company: Castalia Systems
Location: Arlington
Posted on: April 2, 2026

Job Description:

Job Type: Full- Time Workplace Type : Onsite in Arlington, VA Clearance: Active TS/SCI and must be able to obtain a DHS Suitability Must be a U.S. Citizen Benefits: Medical, dental, and vision coverage, 401k matching, generous PTO, paid holidays, professional training opportunities, and even pet insurance to ensure your furry friends are cared for too. Job Summary The DHS?s Hunt and Incident Response Team (HIRT) secures the Nation?s cyber and communications infrastructure. HIRT provides DHS?s front-line response for cyber incidents and proactively hunting for malicious cyber activity. Castalia Systems performs HIRT investigations to develop a preliminary diagnosis of the severity of breaches. Castalia provides HIRT remote and onsite advanced technical assistance, proactive hunting, rapid onsite incident response, and immediate investigation and resolution using host-based, network-based and cloud-based cybersecurity analysis capabilities. Contract personnel provide front line response for digital forensics/incident response (DFIR) and proactively hunting for malicious cyber activity. Castalia Systems is seeking a Cyber Network Defense Analyst (CNDA) to support this critical customer mission. The Cyber Network Defense Analyst uses information collected from a variety of sources to monitor network activity and analyze it for evidence of suspicious behavior. Monitoring and analysis are performed to identify and report events that occur, or might occur, within the network, to protect information, information systems, and networks from threats. CNDAs review data collected to analyze cyber events, and the network environment, to find trends, patterns or anomaly correlations that indicate more serious attacks or future threats. The CNDAs will recommend proactive measures to contain the incident. These proactive measures include, but are not limited to, identification of intruder local changes/suspect interactions, isolation, in-depth digital media analysis, consultation with law enforcement or counterintelligence organizations, development of signatures to detect this malicious behavior and development and deployment of eradication tools. Roles and Responsibilities A qualified candidate will perform the following duties and responsibilities, but are not limited to: The majority of the CNDA?s time (75%) will be spent executing the following tasks: Characterize and analyze network traffic to identify anomalous activity and potential threats to network resources Coordinate with enterprise-wide cyber defense staff to validate network alerts Document and escalate incidents (including events? history, status, and potential impact for further action) that may cause ongoing and immediate impact on the environment Perform cyber defense trend analysis and reporting Perform event correlation using information gathered from a variety of sources within the enterprise to gain situational awareness and determine the effectiveness of an observed attack Provide daily summary reports of network events and activity relevant to cyber defense practices Receive and analyze network alerts from various sources within the enterprise and determine possible causes of alerts Provide timely detection, identification, and alerting of possible attacks/intrusions, anomalous activities, and misuse activities and distinguish these incidents and events from benign activities Use cyber defense tools for continual monitoring and analysis of system activity to identify malicious activity Analyze identified malicious activity to determine weaknesses exploited, exploitation methods, effects on system and information Determine tactics, techniques, and procedures (TTPs) for intrusion sets Examine network topologies to understand data flows through the network Identify and analyze anomalies in network traffic using metadata Conduct research, analysis, and correlation across a wide variety of all source data sets (indications and warnings) Validate intrusion detection system (IDS) alerts against network traffic using packet analysis tools Identify applications and operating systems of a network device based on network traffic Reconstruct a malicious attack or activity based off network traffic Identify network mapping and operating system (OS) fingerprinting activities Assist in the construction of signatures which can be implemented on cyber defense network tools in response to new or observed threats within the network environment or enclave Notify designated managers, cyber incident responders, and cybersecurity service provider team members of suspected cyber incidents and articulate the event's history, status, and potential impact for further action in accordance with the organization's cyber incident response plan Approximately 25% of the CNDA?s time will be spent executing the following tasks: Prepare and update manuals, instructions, and operating procedures Evaluate established methods and procedures and prepare recommendations for changes in methods and practices where appropriate Plan and carry out difficult and complex assignments and develop new methods, approaches, and procedures Conduct analyses and recommend resolution of complex issues affecting the specialty area Ensure optimal use of commercially available products Prepare and present reports Evaluate the effectiveness of installed systems and services Required Qualifications: 5 years of direct relevant experience in cyber defense analysis using leading edge technologies and industry standard cyber defense tools BS Computer Science, Cyber Security, Computer Engineering, or related degree; or HS Diploma & 7-9 years of network investigations experience. Experience successfully developing and deploying signatures Experience detecting host and network-based intrusions via intrusion detection technologies (e.g., Snort) Experience implementing incident handling methodologies Experience implementing protocol analyzers Experience collecting data from a variety of cyber defense resources Experience reading and interpreting signatures (e.g. snort) Experience performing packet-level analysis Experience conducting trend analysis Desired Qualifications: ArcSight (or other SEIM solution) and Python programming experience would be ideal Strong math and science background. Experience with Carnegie Mellon SiLK tool suite Desired Certifications: One or more of the following professional certifications: GNFA, GCIH, GCIA, GSEC, CASP, CySA, PaLMS, FedVTE , Network, Security Physical Requirements/Work Environment Normal office environment. Travel Less than 5%. Company Description Castalia Systems is a proven business partner providing mission critical solutions to the Federal Government. We provide cutting edge solutions from Securing and Managing Data to Systems Engineering and Development. Castalia Systems is a pioneer in Artificial Intelligence Design and Application. With our vast knowledge of our customers? needs and relevant technology, our team is able to bring successful solutions to every mission. We are one-upping our competitors by providing premium IT solutions and platforms with cutting-edge technology so it?s so evident when you compare us with anyone. Disclaimer Castalia Systems is an equal employment opportunity and affirmative action employer and strives to comply with all applicable laws prohibiting discrimination based on race, color, creed, sex, sexual orientation, age, national origin, or ancestry, physical or mental disability, veteran status, marital status, HIV-positive status, as well as any other category protected by federal, state, or local laws. All such discrimination is unlawful, and all persons involved in the operations of the company are prohibited from engaging in this type of conduct.

Keywords: Castalia Systems, Towson , Cyber Network Defense Analyst, IT / Software / Systems , Arlington, Maryland