What is a vulnerability scanner?

A vulnerability scanner is a tool designed to proactively identify weaknesses within an organization’s digital assets. By systematically scanning systems, networks, or applications (depending on the scanner type), it detects known vulnerabilities, misconfigurations, and outdated components. Scanners can be passive or actively simulate potential attack vectors, providing detailed reports that prioritize vulnerabilities based on severity and exploitability.​

Types of vulnerability scanners

Vulnerability scanners can be categorized based on the assets they test:​

• Application vulnerability scanners include dynamic tools (DAST), static analysis tools (SAST), and others. DAST specifically tests running applications from the outside to detect exploitable vulnerabilities in real time. Examples of DAST tools include:
  • Invicti: Enterprise-grade AppSec platform that unifies DAST, SAST, SCA, and API security, using DAST to verify exploitability for other testing methods.
  • Acunetix: The fastest DAST app with proof-based scanning to confirm exploitable vulnerabilities.
  • Burp Suite: A popular penetration testing scanner known for its focus on supporting advanced manual vulnerability testing. 
• Network vulnerability scanners look for vulnerabilities within network infrastructures, including servers, routers, and other connected devices.​ Examples of network scanners include:
  • Tenable Nessus: Widely used for network vulnerability assessments, detecting misconfigurations and compliance issues. 
  • Greenbone OpenVAS: An open-source tool offering comprehensive scanning for network vulnerabilities. 
  • Intruder: Provides continuous network scanning with proactive threat detection.

Examples of detected vulnerabilities

Vulnerability scanners are adept at uncovering a wide array of security weaknesses that attackers commonly exploit. However, the types of vulnerabilities and the testing methods to discover weaknesses are very different for each type of scanner.

Vulnerabilities found by application security scanners

Application-focused DAST scanners examine the live behavior of web apps and APIs to identify exploitable flaws. Commonly detected issues include:

• SQL injection: Allows attackers to manipulate back-end databases by injecting malicious SQL statements through user input fields.
• Cross-site scripting (XSS): Enables the execution of untrusted scripts in a user’s browser, potentially stealing session cookies or credentials.
• Command injection: Enables attackers to inject system commands that the server executes with the privileges of the hosting process.
• Directory traversal: Grants unauthorized access to files and directories outside the intended scope by manipulating file path inputs.
• Security misconfigurations: A broad category that includes insecure HTTP headers, overly verbose error messages, and exposed config files.

Vulnerabilities found by network security scanners

Network scanners inspect infrastructure-level components for weaknesses that may not be tied to the application layer. These include:

• Open ports: System and application ports that are exposed to the internet or internal networks unnecessarily create potential attack vectors.
• Weak encryption protocols: Outdated TLS/SSL versions and cipher suites may allow communications to be intercepted or decrypted.
• Unpatched services: Known vulnerabilities in OS services or installed software that haven’t been updated provide easy entrance points for attackers.
• Default credentials: Devices and software that use default usernames and passwords are easy to compromise.
• DNS cache poisoning risks: Misconfigurations or weaknesses that allow DNS spoofing or redirection attacks.

Real-world example of an exploited application vulnerability

The 2017 Equifax breach, which exposed sensitive information of millions, was attributed to an unpatched Apache Struts vulnerability—a type flaw that a good DAST tool could have been able to identify, allowing timely remediation and potentially preventing a major breach.

What is a SIEM?

Security Information and Event Management (SIEM) systems aggregate, analyze, and correlate log data from various sources within an IT environment. They provide real-time insights into security events, facilitating threat detection, incident response, and compliance reporting.​

Primary functions of SIEM

• Data aggregation: Collects logs from applications, network devices, servers, and more.​
• Event correlation: Identifies patterns and relationships among disparate events to detect anomalies.​
• Alerting and reporting: Generates real-time alerts and comprehensive reports for security teams.​

Examples of security threats detected by SIEM

SIEM systems are instrumental in identifying:​

• Insider threats: Unusual access patterns by employees, such as accessing sensitive data during off-hours.​
• Advanced persistent threats (APTs): Coordinated, stealthy attacks that occur over extended periods.​
• Malware infections: Detection of malicious software activity within the network.​

Real-world example of a SIEM in action

A certain financial services company detected unauthorized access to customer data by an internal employee. The SIEM system flagged atypical access patterns, enabling the security team to intervene promptly and prevent potential data exfiltration.

Key differences between vulnerability scanners and SIEM

While both types of tools enhance security, they differ greatly in purpose and mode of operation—most importantly in SIEM being mostly reactive while vulnerability scanning is mostly proactive.​

Vulnerability scannersSIEM systemsPurposeIdentify and report known vulnerabilities before exploitationMonitor, detect, and respond to security incidents in real timeData sourcesActively and passively scan systems, applications, and networks for weaknessesAggregate logs from various sources like servers, applications, and network devicesOperation modeProactive; scheduled or on-demand scans to find potential issuesReactive; continuous monitoring to detect and respond to ongoing threatsOutputDetailed reports highlighting vulnerabilities with severity ratings and remediation suggestionsReal-time alerts, dashboards, and reports on security events and incidentsResponse mechanismProvide guidance for remediation but don’t take direct actionCan trigger automated responses or workflows to mitigate detected threats

Complementary use of vulnerability scanners and SIEM

Integrating both types of tools offers a holistic security approach:​

1. Proactive identification: Vulnerability scanners highlight potential weaknesses, allowing for timely remediation.​
2. Continuous monitoring: SIEM systems oversee the environment for signs of exploitation or anomalous behavior.​
3. Enhanced incident response: Insights from vulnerability scans can inform SIEM correlation rules, improving detection accuracy

Below is a flowchart illustrating the workflow where vulnerability management and threat detection intersect:

This sequence demonstrates how dynamic application security testing and SIEM can work in tandem: DAST confirms real risks, and SIEM ensures immediate, context-aware response.

Why DAST fills the gap between detection and action

While both vulnerability scanners and SIEMs offer critical insights, they often operate in silos where one identifies potential issues and the other reacts to suspicious behaviors. But what ties detection to meaningful action is validation. This is where dynamic application security testing (DAST) becomes indispensable.

DAST, especially when implemented with proof-based scanning like Invicti provides, verifies whether a vulnerability is exploitable in a live environment. It not only eliminates false positives but also enables fast triage and confident remediation. This validation step bridges the divide between theoretical risk and actionable intelligence.

Unlike SIEM systems that react after something happens—or legacy application scanners that only produce long lists of potential flaws—modern DAST empowers teams to fix what attackers can actually exploit. It brings accuracy, speed, and focus to the vulnerability management process.

Final thoughts

Knowing how vulnerability scanners and SIEM systems differ—and how they complement each other—gives organizations the tools to design a security posture that is both proactive and reactive.

Security isn’t about seeing everything. It’s about seeing what matters and acting on it. A DAST-first approach helps you zero in on real risks, validate them, and ensure they are remediated before exploitation. Combined with SIEM’s ability to detect live threats, this creates a security program that can defend, respond, and evolve.

If you’re looking to bridge the gap between detection and action, consider Invicti. Our DAST platform offers proof-based scanning, scalable automation, and no false positive vulnerabilities in your pipeline—helping you cut through noise and secure what really matters.