Undiscovered Breach Rates Across SMBs: A Deep Dive into Vulnerabilities by Business Size
- jason15065
- Jan 13
- 5 min read
Cyberattacks on small and medium-sized businesses (SMBs) are more common than many realize. Over 60% of SMBs face at least one cyberattack every year, yet a significant portion of these breaches go unnoticed or unreported. This gap in detection and disclosure leaves many businesses vulnerable and unaware of the risks they face. Understanding how breach rates vary by business size reveals why some SMBs remain blind to attacks and why many incidents never reach public awareness.
Breach Rates for Businesses Under 500 Employees
Most SMB reports group businesses with fewer than 500 employees together. Within this broad category:
Over 60% experience at least one cyberattack annually.
About 70% lack rapid breach detection tools.
As a result, an estimated 40–60% of breaches go undiscovered.
Underreporting is common, with 50–75% of breaches not disclosed unless legally required.
This means many SMBs operate without knowing they have been compromised, increasing the risk of prolonged damage.
Higher Risks for Businesses Under 250 Employees
Smaller SMBs typically have weaker security postures than their larger counterparts. For businesses with fewer than 250 employees:
Expected undiscovered breach rates rise to 50–70%.
Unreported breaches likely fall between 60–80%.
These firms often have limited IT resources and less sophisticated monitoring, making it easier for attackers to remain hidden.
The Most Targeted Group: Businesses Under 100 Employees
Businesses with fewer than 100 employees face the highest ransomware targeting, accounting for 37% of ransomware victims. Their breach rates are even more alarming:
Undiscovered breaches estimated at 60–80%.
Unreported breaches between 70–85%.
This group’s vulnerability stems from limited budgets and a lack of dedicated cybersecurity staff, leaving them exposed to stealthy attacks.
Smallest Businesses Face the Greatest Challenges
For businesses with fewer than 50 employees, the situation worsens:
Nearly half have no cybersecurity budget.
One-third rely on free, consumer-grade security tools.
Undiscovered breach rates climb to 70–90%.
Unreported breaches range from 75–90%.
Without proper investment in security, these businesses are often unaware of ongoing compromises, making recovery difficult.
The Most Vulnerable: Businesses Under 25 Employees
The smallest SMBs are the least defended and most fragile economically:
Many have no IT staff.
Detection capabilities are minimal or nonexistent.
Undiscovered breaches are expected to be 80–95%.
Unreported breaches also fall between 80–95%.
This aligns with data showing 78% of SMBs fear a breach could put them out of business. Many cannot afford breach investigations or disclosure, so incidents remain hidden.
Why Breaches Go Undetected or Unreported
Several factors contribute to the high rates of undiscovered and unreported breaches across SMBs:
Lack of monitoring and automation: Only 32% of SMBs use privileged access management (PAM) tools. Most rely on manual or no monitoring, allowing breaches to go unnoticed.
Human error and credential theft: Human mistakes cause 95% of breaches. Phishing alone accounts for about 73% of SMB breaches. These attacks are often stealthy, so victims may never realize they were compromised.
Economic and resource constraints: Many SMBs cannot afford dedicated cybersecurity staff or advanced tools. This limits their ability to detect and respond to breaches.
Fear of reputational damage and legal consequences: SMBs often avoid reporting breaches unless required by law, leading to significant underreporting.
Practical Steps SMBs Can Take
(With Streamline Networks solutions for every step)
While the statistics are concerning, SMBs can improve their security posture with practical actions:
Invest in basic monitoring tools: Even affordable PAM solutions can reduce undetected breaches. Streamline Solution: Privileged Access Management deployment and oversight with 24x7 monitoring security threats
Train employees on phishing awareness: Since human error is a major factor, education helps prevent credential theft. Streamline Solution: Security awareness training and phishing simulation.
Develop an incident response plan: Knowing how to react quickly limits damage and improves recovery. Streamline Solution: 24/7 SOC monitoring with risk factoring incident response.
Consider cybersecurity insurance: This can help cover costs related to breach investigations and disclosures. Streamline Solution: Security assessments, reviews, threat‑vector reporting to help reduce the costs of cyber insurance policy.
Seek external expertise: Streamline Networks it the Solution: As a Managed security service providers (MSSPs) we offer affordable monitoring and response along with full IT services built to meet you need.
Understanding the likelihood of breaches going undetected or unreported by business size helps SMBs prioritize their security efforts. Smaller businesses face greater risks but can take steps to improve detection and reduce the impact of attacks.
📌 Summary Table
Business Size | Estimated % Undiscovered | Estimated % Unreported |
<500 employees | 40–60% | 50–75% |
<250 employees | 50–70% | 60–80% |
<100 employees | 60–80% | 70–85% |
<50 employees | 70–90% | 75–90% |
<25 employees | 80–95% | 80–95% |
Small or Large, the Challenges Are the Same — Big Business Outsources for Help, and So Can You
🏢 Fortune 100 / Fortune 1000 – Estimated % Undiscovered & % Unreported Breaches
📌 1. Estimated % Undiscovered Breaches
The most direct metric available is the percentage of breaches not detected internally by enterprises.
Only 17% of Fortune 1000 organizations detected their own breaches, according to the 2024 Cybersecurity Readiness Report.
This means 83% of breaches were discovered by outsiders (legal teams, regulators, third parties, governments) rather than the company itself.
⭐ Estimated % Undiscovered (Fortune 100 scale): ~80–85%
Fortune 100 companies are included within the Fortune 1000 analysis. Given the uniformity of the report’s findings across the enterprise segment, the best-supported estimate is:
📌 Approximately 80–85% of breaches go undetected internally at Fortune 100–scale companies.
📌 2. Estimated % Unreported Breaches
True “unreported” numbers are not disclosed publicly for Fortune 100 companies. However, major enterprise studies include evidence that:
Over 60% of Fortune 1000 firms had at least one public breach over the last decade — meaning many more occurred but were never publicly disclosed.
A large portion of enterprise breaches are classified as non‑material under SEC rules and therefore are not required to be disclosed.
Most breaches that companies do know about are handled internally unless legally required to publish them.
Given regulatory patterns, legal thresholds, and decade-long breach census data:
⭐ Estimated % Unreported (Fortune 100 scale): ~50–70%
This aligns with:
Only mandatory disclosures becoming public
Non‑material or undetected breaches remaining unreported
Known enterprise reporting behaviors observed across Fortune‑ranked companies
📊 Summary Table: Fortune 100 / Fortune 1000 Enterprise Breach Metrics
Metric | Best-Supported Estimate | Source Basis |
% Undiscovered | ~80–85% | 83% of breaches detected externally, not by internal systems. [cybersecur...siders.com] |
% Unreported | ~50–70% | Based on gap between public breaches and known enterprise breach incidence. [bitdefender.com] |
🔍 Why These Numbers Matter
Even the largest, best‑funded companies in the world:
Spend billions on cybersecurity
Maintain massive SOC teams
Deploy advanced EDR, SIEM, SOAR, and AI systems
Yet still fail to detect the majority of breaches internally. And even when they do, they often do not report them publicly unless legally compelled.
This contrast provides powerful context when educating small businesses:
If Fortune 100 companies — with the best tools and budgets on earth — miss 80% of their breaches, what chance does a 50‑employee business have without help? Streamline Networks we have your solution. Total Protection Plan - Affordable, Simple, Secure.
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