SIEM and Security Log Monitoring

No, though a great many SIEM deployments end up being exactly that, at considerable expense. Storage answers the question "can we produce the logs if asked". A SIEM earns its cost by correlating events across sources (a failed login series in your identity provider, a successful login from an unusual location, a new inbox rule, then unusual file access on a server) and recognizing that sequence as one story rather than four unrelated entries in four systems. Correlation and the detection logic written on top of it are the product. Storage is the prerequisite.

Fewer than most vendors would like to ingest. Identity and authentication logs are the highest value by a wide margin, because credential abuse is behind so many intrusions. After that: endpoint detection telemetry, email and collaboration platform audit logs, firewall and VPN, server and domain controller security logs, and critical business applications. Ingesting everything indiscriminately raises cost and dilutes signal. We would rather start with the sources that produce detections and expand deliberately.

It depends on your obligations, and the defaults are almost always shorter than they need to be. Several frameworks and contracts specify a minimum retention period, and cyber insurers increasingly ask. Beyond compliance, there is a practical argument: intrusions are frequently discovered weeks or months after they began, and if your retention is 30 days, the evidence of how it started no longer exists. We size retention against your specific requirement and against the investigation window you would realistically need.

It is a market term rather than a defined standard, and its meaning varies enormously between providers. It can mean a fully staffed facility with continuous shifts, or a platform with detections and a defined escalation process, or something in between. Rather than rely on the label, ask any provider (us included) three concrete questions: which hours are actually covered, what happens to a detection raised outside those hours, and which containment actions the provider is authorized to take. Our coverage windows and escalation paths are set out in your agreement in specific language rather than implied by a term.

Predominantly data volume (how many sources, how chatty they are, and how long the data is retained) plus the engineering effort to write and maintain detections that fit your environment. Cost surprises usually come from ingesting a high-volume source such as verbose firewall or proxy logging without deciding what detection it supports. We scope sources against the detections they enable and against your retention requirement, and we tell you which sources are cost drivers before they are turned on.

Often yes, for a specific reason: endpoint tooling sees the endpoint. An attack that begins with a stolen credential used against a cloud service, adds a mail-forwarding rule, and then quietly downloads a shared folder may never touch a managed device in a way endpoint detection would flag. Correlating identity, email, and cloud audit logs is what makes that sequence visible. If your risk is concentrated on managed devices, endpoint detection alone may be a reasonable place to stop for now, and we will say so.