Senior Security & Systems Engineer

One Source Communications LLC

15h

About The Position

The Senior Systems & Security Engineer is a senior, hands-on responder responsible for stabilizing, containing, and rebuilding client environments during and after cybersecurity incidents. This role is engaged when environments are already compromised, degraded, or operating within significant security gaps and requires rapid, decisive technical action. The engineer works closely with the Incident Response team to ensure response and remediation efforts are executed efficiently, while maintaining focus on threat containment, root cause analysis, and long-term security hardening. This is not a monitoring-only or compliance-focused role. The ideal candidate has real-world incident response experience and is comfortable operating in high-pressure, client-facing situations to: Stop active threats and attacker movement Contain impact and restore operational control Identify root cause and systemic security failures Rebuild and harden security controls correctly Improve detection, visibility, and response capability Reduce the likelihood and impact of future incidents (This position does require travel up to 50% of the time)

Requirements

Ability to travel up to 50% of the time.
5+ years of experience in information security with a strong focus on incident response and remediation.
Demonstrated experience responding to real-world security incidents.
Hands-on experience with EDR, security monitoring, and endpoint and identity remediation.
Strong understanding of attacker techniques, lateral movement, and persistence mechanisms.
Working knowledge of scripting and automation (PowerShell, Python).
Strong communication skills with experience supporting client-facing response efforts.
Bachelor’s degree in Computer Science, Information Security, or equivalent hands-on experience.

Nice To Haves

Security certifications such as CISSP, CISM, CEH, or CompTIA Security+ preferred.
Experience in MSSP, consulting, or multi-client environments preferred.

Responsibilities

Respond to active security incidents including ransomware, account compromise, malware outbreaks, and lateral movement.
Analyze endpoint, identity, network, and log telemetry to determine scope, root cause, and attacker behavior.
Execute containment actions across endpoints, identity platforms, and network infrastructure.
Support eradication and recovery efforts to ensure secure restoration of services.
Provide clear technical direction during live incident response activities.
Identify control failures, misconfigurations, and visibility gaps that enabled the incident.
Design and implement remediation plans addressing both immediate threats and underlying weaknesses.
Perform security hardening across endpoints, servers, identity systems, and networks.
Remove persistence mechanisms and validate clean recovery.
Rebuild security baselines to prevent repeat incidents.
Deploy, configure, and maintain modern security platforms, including:
Endpoint Detection & Response (EDR)
Security telemetry and log analytics platforms (SIEM, XDR, log pipelines)
ELK / Elastic stack
Email Threat Protection
Integrate security telemetry and data sources to improve detection accuracy and investigation speed.
Improve logging, alerting, and response workflows in environments with limitedor fragmented visibility.
Conduct post-incident assessments and gap analyses.
Identify vulnerabilities, misconfigurations, and systemic security debt.
Implement preventative controls to reduce attacker dwell time and blast radius.
Support vulnerability management and long-term risk reduction initiatives.
Secure identity platforms using Active Directory, LDAP, SAML, and OAuth.
Respond to identity and cloud-centric incidents including SSO abuse, token theft, and SaaS compromise.
Assess and harden network security controls including firewalls, IDS/IPS, VPNs, VLANs, and TLS.
Apply cloud security best practices across AWS, Azure, and Google Cloud environments.
Identify and mitigate common application security vulnerabilities such as SQL injection, XSS, and CSRF.
Introduce scripting and automation (PowerShell, Python) to accelerate response and reduce manual effort.
Document rebuilt architectures, security controls, and response procedures.
Collaborate closely with the Cyber Security Incident Response Project Manager to align technical execution with timelines and deliverables.
Provide technical guidance and mentorship during response and remediation efforts.
Contribute to future-state security architecture and resilience planning.