SIEM or MDR? Choosing the Right Security Monitoring Model for SMEs

SIEM is software. MDR is a service. That’s the short answer, but the decision itself isn’t as clean. You buy a SIEM, install it, and it starts collecting data, correlating events, generating alerts — then a separate question opens up: who actually reads that alert at 3am, and who acts on it. With MDR, a team is already doing that job. You mostly see the report afterward.

That’s where most confusion happens on the ground. A company tells us “we have a SIEM, we’re covered,” and when I ask who last checked the console, the answer is usually “the firm that installed it” — six months ago.

Both get sold under the same “security monitoring” label, which makes the buying decision harder than it should be. In practice they answer different questions: SIEM answers “how do I see and log what’s happening,” MDR answers “if something goes wrong, who responds, and how fast.”

What SIEM actually does — and doesn’t

SIEM (Security Information and Event Management) pulls logs from everywhere — firewalls, servers, Active Directory, cloud apps — and correlates them in one place. In theory, it can catch something like a user logging in from Ankara at 2am and again from Germany five minutes later.

In practice, three problems show up:

• Tuning takes weeks after setup; skip it, and you get thousands of noisy alerts (“alert fatigue”)
• Someone needs to watch the console 24/7 — in an SME, that rarely belongs to anyone specifically
• License and storage costs scale up with data volume, often faster than expected

SIEM gives you visibility and access to the data. It doesn’t give you the people needed to turn that data into an actual response. Think of it as the system that pipes every camera in a building into one screen — the resolution stops mattering if nobody’s watching that screen, or running when something looks wrong.

What MDR adds: not the technology, the team watching it around the clock

MDR (Managed Detection and Response) usually sits on top of EDR/XDR sensors, but the real difference is what happens after an alert fires. It doesn’t wait. A team takes the first response on your behalf — isolating a device, killing a process, locking an account — then calls you.

A case from a client last month makes the point well: ransomware started encrypting files on one workstation, and the MDR team isolated it from the network automatically, within minutes. By the time we were notified, the incident was already contained. With a standalone SIEM, if nobody happens to be watching the console, the same alert might sit unread until morning.

The real cost and staffing picture

	SIEM (standalone)	MDR
Setup	Weeks (tuning included)	Days
24/7 monitoring	Your own team, or a separate SOC contract	Included in the service
Response	Your team handles it	Provider handles it, you approve
Monthly cost trend	Grows with data volume	Fairly stable per endpoint
Typical SME fit	50+ staff with an in-house security team	5-150 staff without the budget for a dedicated SOC

A 20-30 person company rarely manages to run a SIEM efficiently on its own; for that same budget, MDR usually covers the same ground with less risk and a more predictable bill. There’s also a cost most companies don’t plan for: log retention. Storage bills climb quietly as data volume grows, and a lot of businesses only notice it a year in.

So is SIEM ever unnecessary?

No — it just serves a different purpose. If you need to answer “who changed what, where, and when” for a KVKK audit, sector-specific compliance (finance, healthcare), or a forensic review after an incident, SIEM’s log archive is hard to replace. In some growing companies we work with, both run side by side: SIEM for records and compliance, MDR for real-time response.

Which one fits your situation

• No dedicated IT/security team, or just one or two people: MDR. You can’t realistically staff 24/7 monitoring yourselves.
• KVKK or sector audit history, with long-term log retention requirements: SIEM (for the archive) plus MDR (for response).
• Only trying to check a compliance box: SIEM alone might satisfy the paperwork, but it won’t provide real protection on its own — worth treating those as two separate goals.
• 10-150 staff, handling sensitive data, without the budget or headcount for a SOC: MDR gets you there fastest with the least risk.

FAQ

We already have a firewall and antivirus — why add MDR? Firewalls and antivirus block known threats. MDR catches what slips past those — fileless attacks, logins with stolen credentials — through behavioral analysis, and a person stops it, not just an alert.

Does moving to MDR waste our existing security investment? No. MDR typically sits on top of your existing EDR or antivirus product; you’re adding a monitoring and response layer, not replacing what you already have.

Isn’t MDR too big a commitment for a small company? It’s priced per endpoint, so the monthly cost stays predictable even at 10-20 staff. The real comparison isn’t “what MDR costs” versus “nothing” — it’s MDR’s cost against the downtime and data loss an unmonitored incident would cause.

If we already have a managed IT contract, does MDR need to be separate? Usually not. MDR can be folded in as the security layer of a managed IT service — one vendor, one report, instead of juggling two.

If you’d like help figuring out which model fits your scale, get in touch.