NIST CSF 2.0 Detect Function for Small & Mid-Size Businesses

The Detect function is the early warning system of your cybersecurity program. While Protect tries to prevent attacks, Detect assumes some attacks will get through and focuses on finding them as quickly as possible. The faster you detect an attack, the less damage it causes. This is where most small businesses have the biggest gap. IBM's Cost of a Data Breach Report consistently shows that the average time to detect a breach is over 200 days. For small businesses without dedicated security monitoring, it can be even longer. Many small businesses only discover breaches when a customer complains, a bank calls about fraud, or ransomware locks their files — by which time the damage is done. The problem is that traditional detection tools — SIEMs, SOCs, EDR platforms with 24/7 monitoring — are designed and priced for enterprises. A small business cannot afford $5,000-$20,000 per month for a managed SOC. But the Detect function does not require enterprise tools. It requires a structured approach to monitoring that catches the threats most likely to affect your business. Cyber Defense Agent was designed to fill this gap. By providing continuous external monitoring at $149/month, CDA gives small businesses a Detect capability that would otherwise be inaccessible.

The Detect function in CSF 2.0 has two categories: DE.CM — Continuous Monitoring. Ongoing monitoring of assets to find anomalies, indicators of compromise, and other potentially adverse events. This includes monitoring networks, computing environments, personnel activity, and external service provider activity. DE.AE — Adverse Event Analysis. Analyzing detected anomalies to characterize the events, determine their potential impact, and support response decisions. This means understanding what a detection means — is it a real threat or a false positive? How severe is it? What should we do? For small businesses, implementing Detect means establishing monitoring in three layers: External monitoring watches your internet-facing infrastructure for changes, vulnerabilities, misconfigurations, and exposures. This is what Cyber Defense Agent provides — continuous assessment of your attack surface as seen from the outside. Endpoint monitoring watches your computers and devices for malicious activity. Modern EDR (Endpoint Detection and Response) tools like Microsoft Defender for Business, SentinelOne, or CrowdStrike Falcon Go provide this capability at price points accessible to small businesses. Log monitoring watches your systems for suspicious activity patterns — failed login attempts, unusual access times, large data transfers, account lockouts. For small businesses, start with the built-in logging and alerting capabilities of your email platform and cloud applications. You do not need all three layers on day one. Start with external monitoring (CDA) and endpoint protection, then add log monitoring as your program matures.

Cyber Defense Agent is purpose-built for the Detect function. Every feature maps directly to DE.CM (Continuous Monitoring) and DE.AE (Adverse Event Analysis). Continuous external scanning — CDA runs 100+ security checks against your internet-facing infrastructure on a weekly or daily schedule. Each scan monitors for: TLS/SSL certificate changes and expirations, new or changed open ports and services, DNS record modifications, email authentication configuration changes (SPF/DKIM/DMARC), security header additions or removals, new subdomains or exposed assets, and web application security indicators. Change detection and alerting — CDA does not just check your posture; it tracks changes over time. If a previously secure configuration degrades — a certificate expires, a new port opens, email authentication weakens — CDA detects the change and alerts you. This is the essence of continuous monitoring: knowing not just where you stand, but when something changes. Adverse event analysis — When CDA finds an issue, it does not just flag it. It categorizes the severity, explains the potential impact, maps it to NIST CSF and CIS Controls, and provides specific remediation guidance. This analysis helps you understand whether a finding is critical (an exposed database port) or informational (a missing optional security header). Cyber Defense Score trending — Your score over time is a detection metric. A declining score indicates your security posture is degrading, which could signal a configuration change, a new vulnerability, or active compromise. Monitor your score trend as a high-level detection indicator. The result: for $149/month, CDA gives you a continuous external Detect capability that addresses the most common and most dangerous attack vectors for small businesses. Combined with endpoint protection ($5-$15/seat/month), you have meaningful Detect coverage at a fraction of enterprise SOC costs.

Here is a practical, budget-friendly detection program for small businesses: Tier 1: External monitoring with CDA ($149/month). This is your foundation. CDA monitors your attack surface continuously and alerts you to changes and vulnerabilities. It catches the threats that come from outside your network, which account for the majority of small business attacks. Tier 2: Endpoint protection ($5-$15/seat/month). Deploy a modern EDR solution on all computers and devices. Microsoft Defender for Business is included in Microsoft 365 Business Premium and provides excellent detection capabilities. If you are not on Microsoft 365, consider SentinelOne or CrowdStrike Falcon Go. Tier 3: Email monitoring (often free with your email platform). Enable audit logging in your email system. Set up alerts for: multiple failed login attempts, logins from unusual locations, email forwarding rule changes (a common BEC indicator), and large outbound data transfers. Microsoft 365 and Google Workspace both provide these alerting capabilities at no additional cost. Tier 4: Cloud application monitoring (free-$500/month). Most cloud applications provide audit logs and alerting. Enable them for your critical applications — practice management, CRM, financial software. Focus on: admin account activity, permission changes, data export events, and API access. Total detection program cost for a 10-person company: $200-$400/month, or $2,400-$4,800/year. This is a fraction of the cost of a managed SOC but provides meaningful detection across external, endpoint, and application layers. Document your monitoring program: what you monitor, how frequently, who receives alerts, and how alerts are investigated. This documentation is part of your NIST CSF evidence and demonstrates your Detect capability to regulators and insurers.