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Introduction
As web applications continue to grow more complex, securing them becomes an increasingly difficult task. Attack surfaces expand as new features are added, third-party components integrated, and codebase evolves. While traditional vulnerability assessments provide value, they only examine applications statically and cannot account for dynamic behaviors or hidden vulnerabilities exploitable during runtime. This is where dynamic application security testing (DAST) plays a pivotal role. By simulating real-world attacks against a live application, DAST tools can uncover a wider range of issues not found through static means alone.
What is DAST?
Dynamic application security testing involves automating the process of detecting security weaknesses in web applications during runtime. DAST scanners launch authenticated and unauthenticated attacks against live applications to mimic the activities of both authorized and malicious users. These attacks probe for vulnerabilities like injection flaws, broken authentication, sensitive data exposure, cross-site scripting (XSS), and more. DAST offers a much more accurate view of an application’s real-world security posture compared to static analysis alone.
Conducting the Scan
A typical DAST scan consists of a few key steps. First, the scanner crawls the target application to map its structure, endpoints, parameters, cookies, forms, and other interaction points. It then generates custom payloads based on common exploits and the target’s specific technologies. The scanner launches attacks by sending crafted inputs to endpoints and observing the responses. Any anomalies, unusual behavior, or errors are flagged as potential issues for further review. Attack coverage also improves over time as learning engines in DAST tools analyze results to develop new techniques.
Typical Findings from a DAST Scan
Among the most common vulnerabilities uncovered by DAST scans are:
Injection Flaws: DAST simulates SQL, OS command, and other injection attacks by encoding malicious input. Issues arise if the app fails to sanitize input before using it in queries, commands, or functionality.
Broken Authentication and Session Management: By brute forcing or guessing credentials, cookies, and tokens, DAST identifies weak or broken authentication and improper session handling.
Sensitive Data Exposure: Scanning checks if sensitive data like passwords, personal info, files, and APIs are exposed to unauthorized access through configuration flaws or missing access controls.
Cross-Site Scripting (XSS): XSS attacks involve injecting client-side scripts through inputs. DAST finds XSS by feeding JavaScript payloads and checking output for embedded scripts.
Cross-Site Request Forgery (CSRF): CSRF involves tricking users into submitting requests they don’t intend to. DAST IDs CSRF by forging unauthorized requests to applications without proper anti-CSRF controls.
Business Logic Flaws: DAST explores app logic flows and checks how inputs alter control or functionality. Flaws arise if improper or dangerous flows are possible through user inputs.
Improper Input Validation: DAST submits oversized, malformed, encoded, and dangerous inputs to identify weak validation filters insufficiently sanitizing inputs.
The Benefits of Regular DAST Scanning
By catching vulnerabilities that evade static scanners, DAST provides an essential layer of security assurance for modern web applications. Regular DAST scans:
– Improve visibility into real threats by emulating hacker techniques against live systems.
– Catch flaws that only surface dynamically through specific user interactions or sequence of inputs.
– Help prioritize remediation of high risk vulnerabilities before exploitation.
– Reduce Mean Time to Remediate (MTTR) by automating vulnerability discovery and reporting.
– Enforce secure coding practices by integrating scans into SDLC for pre-deployment checks.
– Continuously monitor applications for new issues introduced through code or configuration changes.
– Scale testing across large, complex application estates that manual pentesting could not effectively cover.
Best Practices for Effective DAST Usage
To maximize value from DAST, organizations should:
– Perform scans regularly as part of dev/test cycles rather than just annually. Issues are found faster this way.
– Scan production applications to identify vulnerabilities attackers could exploit and patch them immediately.
– Correlate DAST findings with runtime logs, errors, and other observability data for accurate remediation.
– Use authenticated scans whenever possible to identify vulnerabilities requiring special access.
– Integrate scans with existing tools like bug trackers for automated vulnerability management.
– Perform selective rescan of high risk areas as remediation is completed to validate fixes.
– Analyze scan results with developers to improve security practices, architecture, and training over time.
– Select DAST solutions with robust coverage of modern technologies, customized attacks, and ML-powered learning for continuous improvement.
By proactively catching flaws via DAST that evade static tools, organizations can reduce exploitation risks, ensure compliance, and enhance overall application security posture in today’s evolving threat landscape. When applied as part of a collaborative DevSecOps strategy, DAST delivers great value for both development and security teams.
