For nearly every company, the sensible choice is to buy the endpoint agent and build the response process around it. A DIY sensor means owning kernel-level code, detection research and constant upkeep. The part worth building in house is how your team investigates, decides and acts.
What would building EDR actually involve?
EDR software records activity on a device, detects suspicious behavior, and lets responders investigate and contain the machine. To build that yourself you would need to write and maintain:
- A sensor that runs on every operating system you support and watches processes, files, network and logins.
- A transport and storage pipeline for the events.
- Detection logic mapped to attacker behavior. MITRE ATT&CK is a knowledge base of adversary behavior commonly used to organize it.
- A console for search, investigation and response actions such as isolating a host.
- Updates, tamper resistance and a plan for operating system changes.
Each piece is a product. Operating system updates can break low-level sensors, and the work does not end.
Where do teams sometimes build?
Some organizations use open source components for specific jobs, such as collecting host telemetry into their own logging system, and write their own detections on top. This is a middle path: assemble, not invent. It can fit a team with strong engineers, unusual platforms, or strict control over data. It still needs people to maintain it indefinitely.
What does buying cost, beyond the price?
Buying is not free of work. You still need an accurate device inventory, which NIST SP 800-53 control CM-8 describes, a policy, tuning, an on-call path and authority to isolate machines. Many EDR projects stall because the agent is deployed and nobody owns the alerts.
How should you decide?
Use five questions.
Do we have unusual platforms? If your endpoints run something commercial agents do not support, building or assembling may be unavoidable. Check support before concluding that.
Who would maintain it? Name the engineers, and their share of time. If the answer is "whoever has spare time", do not build.
What is our detection skill? Writing good detections takes ongoing research. A small team will do better using vendor content and tuning it.
What are our data constraints? If data cannot leave your environment, look at products with self-hosted options, or an assembled design. Ask vendors about deployment choices instead of assuming.
What is the opportunity cost? Every engineer hour on a sensor is an hour not spent on your product or on application security.
A constructed comparison
A fifty person company has two security engineers. Plan A builds a Linux and macOS telemetry collector and a rule set, estimated at a few months by an enthusiastic engineer. Plan B buys an agent, then spends the same months on inventory, response playbooks and tuning. By month six, Plan A has a collector with no response actions and a backlog of operating system quirks. Plan B has coverage, tested isolation and a trained on-call rota. The company and numbers are invented for illustration.
What is worth building in house?
Response playbooks. Who may isolate a machine, how to confirm, how to communicate. NIST SP 800-61 Rev. 3 helps you place these inside wider risk management.
Tuning and exclusions. Knowledge of your environment is your advantage.
Integrations. Tickets, chat, identity and asset inventory connected to alerts.
Exercises. Harmless, agreed simulations that test whether detection and response work.
What if budget is tight?
Look first at what is already included with operating systems and productivity suites you pay for, and at managed options that bundle monitoring. Compare on your own needs and ask for written quotes. Do not assume that a free component is cheaper once staff time is counted.
What to do
- Inventory devices and operating systems.
- List who could maintain a custom sensor and the time they have.
- Check commercial support for your odd platforms before deciding to build.
- Pilot one or two products on a mixed group.
- Build the response process, tuning and exercises in house.
- Revisit the decision yearly.
Where Safeguard fits
Safeguard does not offer EDR and does not replace it. It works on the application and software supply chain side, which endpoint tools do not cover, such as reachability analysis for dependencies and release policies.
Quick check
Can open source replace a commercial EDR?
Parts of it can, for collecting telemetry. Replacing the whole system also needs detection content, a console, response actions and ongoing maintenance.
What should we definitely not outsource?
Decisions about what is allowed to be isolated or shut down, since those depend on your business.
Sources
Last reviewed: 18 October 2026.
