How to cut costs and boost automation with Microsoft Defender

Microsoft will tell you Defender is free, and the presenter in this LimaCharlie session concedes the point with a caveat that turns out to be the whole story. The antivirus engine bundled into Windows is genuinely good, one of the better ones for the platform. But "free" in Microsoft's vocabulary means "bundled into a subscription," and the subscription is where a service provider's economics quietly come apart. The interesting tension here is not Defender versus some competitor. It is the gap between the telemetry your endpoints are already producing and the price Microsoft charges you to actually see and search it.

The licensing model fights the way an MSSP runs

Defender capability rides on E3 or E5 licenses, and those licenses are priced per user, not per endpoint. For an MSSP that one detail poisons the whole planning exercise. Do you size a customer by headcount or by deployed machines? Headcount drifts as a client hires and fires, and you have to keep the licensing reconciled against a number you do not control. Sometimes the customer brings their own license, sometimes you carry it, and the blend of per-user and per-endpoint billing makes it hard to model cost cleanly across a tenant base. The speaker is blunt about the trust problem underneath it: a customer can claim a hundred employees, and you are left managing the gap between what they say and what they run.

The product naming makes it worse. There is Defender antivirus, Defender for Endpoint, Defender 365, and, the speaker jokes, probably Defender for AI next. Working out which feature lives in which tier took him real homework, enough that he built a table and offered to send the slides out afterward. That homework is exactly the work a provider does not want to repeat for every prospect.

You are often paying to see data you already have

Here is the part that should bother anyone running margins. The strong free antivirus also carries the Windows firewall, some OneDrive and account telemetry, and controlled folder access. Much of that signal already lives in the Windows logs sitting on the box. Yet Microsoft tends to surface it only in the higher plans, so you can end up paying extra for visibility into data the system is generating for free. The speaker's framing is that you spend the session "harvesting all this information from the Windows system," and then sometimes pay again just to look at it.

Retention is the second trap. Even on paid Defender tiers you might get up to 180 days of log retention, but retention is not the same as searchable. You are lucky, he says, to get 30 days you can actually query. For threat hunting that leaves two options, both costing money: buy add-ons, or pump the data into Microsoft Sentinel. And Defender for Endpoint Plan 1 and Plan 2, which the speaker notes a partner can get standalone at roughly $3 and $5.20 per month, mostly add configuration and networking control. They do not meaningfully widen the log visibility you could already collect.

The cost line that decides the argument

Sentinel is where the abstraction becomes a number. Pay-as-you-go ingest runs about $5.22 per gigabyte, dropping toward roughly $2.50 per gigabyte only at high committed daily volumes, similar to how Splunk tiers down. For high-velocity sources, workstations, servers, the Azure environment itself, that meter compounds fast. Worse, Defender on its own logs mostly when it catches something against a known signature. That detection is a useful alert, but it arrives without the surrounding telemetry an analyst needs to investigate or to satisfy an audit, so the broader Windows event logs end up flowing into Sentinel anyway, on the meter.

LimaCharlie's answer is to flatten the meter. The platform charges $3 per month per sensor, and that price includes all the streaming telemetry you bring in: the default agent events, Windows event logs, the Windows Defender data, security and system logs, the lot. It also includes 365 days of searchable retention, a full year, which the speaker rightly calls unheard of in a SIEM space where legacy tools get expensive past 30, 60, or 90 days. There is no separate ingest charge sitting on top. For a provider, the value is not that it is cheaper in the abstract. It is that per-tenant cost becomes a fixed line you can forecast as you add customers, rather than a variable you discover at the end of the month.

Collection and automation, across every tenant

LimaCharlie pulls the Defender antivirus telemetry through artifact collection, and the endpoint protection extension makes standing it up short: subscribe in the add-ons, do a little configuration, and the platform syncs the rules, grabs the Windows Defender log path, wires it into artifact collection, and deploys a set of detections out of the box. You can also layer on file integrity monitoring for PCI use cases, ingest logs from custom applications, and run YARA scans, including rootkit hunting on Linux and Mac where Defender coverage thins out.

The coverage is genuinely cross-platform: Windows, Linux, Mac, Docker, and the cloud. Answering an attendee, the speaker confirmed the Linux agent runs in AWS EC2, a Docker agent gives container visibility, and EKS logs along with telemetry from AWS, Azure, and Google land in one central repository. On Mac, the agent collects its own telemetry and, where Microsoft is deployed, will report whether a control like XProtect is enabled, though he was candid that this is lighter than what you get on the Windows side.

What ties it together for the ICP is that all of this is multi-tenant and API-first by design, which is why the platform is a common choice for MSSPs and MDRs. The speaker describes it as the least known security vendor with hundreds of thousands of deployed agents, and points to customers who operate entirely through the API without ever opening the UI. Detections can fire Python playbooks directly, with SOAR available through partners like Tines. For a provider with developers on staff, triggering a script straight off a detection is the lever that turns Defender collection from a per-customer chore into automation applied across the whole fleet at once. That is the real distinction. Microsoft sells you a license per user and charges again to search what your endpoints already produce. The alternative on offer is a flat per-sensor cost, a year of searchable data, and the freedom to automate it everywhere.