SIEM without maturity is an expensive noise machine
A good SOC starts with solid telemetry and defined scenarios, not with buying a platform.
SIEM systems are sold as the solution to security monitoring. Connect your sources, configure the rules, and you will have visibility into what is happening in your infrastructure. That is true, but incomplete. Between "SIEM is installed" and "SIEM is working" lies a distance that many organisations never close.
I have seen several deployments where the system was running - in the sense that it collected logs and generated alerts. But when asked "what was happening in the infrastructure three weeks ago on Monday around midnight", the team stared at the screen and shrugged. The data was there; making sense of it was not possible.
Why the box does not solve the problem
SIEM is a tool for processing and correlating events. For it to work, several things are needed, each requiring its own effort.
First, you need good telemetry. Sources must deliver events in the right volume and format. Too little - you will miss the attack. Too much - you will drown in noise and miss it anyway. Most organisations start by connecting everything available and get exactly that noise. What useful signal can be extracted from logs as a data source, not garbage even before a SIEM exists is a separate question.
Second, you need correlation rules written for real attack scenarios in your real environment. The default rule set that ships with any platform covers generic signatures but knows nothing about your network topology, your users, or your specific risks. Generic rules generate generic alerts.
Third, you need people who know how to work with all of it. An alert is not an incident - it is a signal for investigation. Investigation requires time, expertise, and a baseline understanding of what normal looks like in this environment.
What happens without maturity
The typical picture: SIEM is configured, alerts are frequent, and the team quickly learns to ignore them. This is not negligence - it is a natural response to a volume that cannot be processed meaningfully. After a few months the system runs for show: logs are written, alerts accumulate, real monitoring does not happen.
This is not a neutral situation. It creates an illusion of protection where none exists and costs real money - licences, hardware, log storage.
There is another side to it: a company that overestimates its SIEM coverage stops investing in other controls - network segmentation, privileged access management, vulnerability tracking - on the assumption that "SIEM is watching". Which security metrics actually mean something to executives is directly connected: if the KPI is "number of alerts processed," the incentive to tune the system correctly disappears. But it is only watching where it is connected, and only for the scenarios it has been given.
What real monitoring starts with
Before thinking about the platform, it is worth answering a few questions.
What event sources do we have and what do they actually produce? It is common to discover that key systems either do not write logs at all, or write in a format that cannot be parsed without additional work.
Which attack scenarios are most relevant for us? This is a question about the threat model, not the platform. Password brute force, compromise of an administrator account, data exfiltration via email - these are different scenarios with different indicators.
Who will respond to alerts and how fast? If there is no answer, alerts will accumulate.
A filter before the budget
Before approving spending on a SIEM, these questions are worth asking:
- Do we have a list of critical assets whose events should be monitored first?
- Have we written at least a minimum set of scenarios - what exactly are we looking for and what counts as an anomaly?
- Is there a dedicated resource for working with alerts - a person or a team?
- Is baseline telemetry configured on key systems before connecting them to the SIEM?
- What does success look like in six months - what specifically should improve?
If the answers are not there, the SIEM will be an expensive noise machine. Process maturity - not the platform - is what determines the outcome.