Dynamic application security testing (DAST) has become an indispensable tool for securing modern web applications. As attacks grow ever more sophisticated, organizations must test their apps and APIs from the outside-in to find vulnerabilities that put data and operations at risk.
This comprehensive 2800+ word guide will teach you everything you need to know to pick the right DAST scanner for your needs. You‘ll learn:
- What is DAST and how it works
- Key benefits of DAST testing
- How DAST compares to SAST and other methods
- Top 10 commercial and open source DAST tools reviewed
- Head-to-head comparison between top DAST vendors
- Best practices for integrating DAST scans
- When to combine DAST with other testing approaches
- And more…
Let‘s start from the beginning and build up your DAST knowledge step-by-step.
What is DAST and How Does it Work?
DAST, or dynamic application security testing, is a black box testing method that analyzes applications from the outside while they are running to find security vulnerabilities.
The key advantage of DAST over white box methods like static analysis (SAST) is that it tests applications the same way attackers exploit them – through the user interface and APIs. This allows DAST to find issues like injection flaws, improper access controls, and business logic errors that tools analyzing source code can miss.
Here is how DAST scanners work in 4 steps:
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Map the attack surface: DAST crawlers inspect the application to discover all available interfaces – this includes user pages, APIs, back-end systems, etc. This mapping establishes the attack surface to be tested.
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Test interfaces: Using the attack surface map, DAST launches exploits and attacks against inputs and APIs to probe for vulnerabilities. Attacks may include SQL injection, XSS, business logic manipulation, or even brute force.
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Analyze responses: The DAST engine observes application responses to attacks to detect behavior indicative of successful exploitation like error messages, missing access controls, or data exposure.
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Report findings: Finally, the DAST tool generates a report listing confirmed vulnerability findings ranked by severity along with remediation guidance for the dev team.
Unlike SAST tools that require access to source code, DAST takes an outside-in, black box approach to find real exploitability issues in running systems. This is why DAST and SAST perfectly complement each other in a comprehensive AppSec program.
Key Benefits of DAST Security Testing
DAST provides major benefits over manual pen testing and many other AppSec testing methods:
Finds 0-day issues: DAST uses advanced fuzzing and attack algorithms to uncover previously unknown flaws missed by humans and source code analysis.
Tests apps as attackers see them: By analyzing only the running application, DAST finds issues that exist in production systems regardless of whether it traces back to a flaw in source code.
Broad vulnerability coverage: Leading DAST tools have 100s of attack forms covering the entire OWASP Top 10 and beyond.
Faster and cheaper than pen testing: Automated scanning provides a level of coverage no human pen tester can match in terms of hours spent.
Easy integration into CI/CD pipelines: DAST scans can execute on every commit or deploy without slowing release velocity.
Prioritized results: Smart DAST tools provide precise findings with proof-of-concept to focus remediation efforts on the riskiest bugs first.
Framework for compliance: DAST results provide evidence of AppSec due diligence for compliance with regulations like PCI DSS.
DAST vs SAST: Key Differences
While DAST takes an outside-in approach, SAST (static analysis) adopts an inside-out tactic by analyzing source code for security issues.
Here are the main differences:
| DAST | SAST |
|---|---|
| Tests externally from running systems | Analyzes source code internally |
| Black box testing | White box testing |
| Finds exploitability issues | Finds coding flaws |
| Broad coverage beyond OWASP Top 10 | Narrow, standards-based coverage |
| Requires deployment first | Shifts left to integrate early |
| Higher false positive rate | Lower false positive rate |
In essence, DAST finds deploy-time issues you can exploit while SAST reveals implementation & design issues that may pose future risk.
That‘s why DAST and SAST perfectly complement each other to provide comprehensive AppSec across the entire software development lifecycle. Leading application security platforms like Contrast combine SAST, DAST, and more for unified coverage.
Now let’s explore some of the top commercial and open source DAST solutions available today.
Top 10 Commercial DAST Tools
1. Contrast DAST
Contrast Security‘s commercial DAST offering combines highly accurate vulnerability scanning with seamless integration across the entire development lifecycle.
It leverages Contrast‘s deep AppSec telemetry across analyzed code, test suites, and running production applications to link DAST results directly to impacted code. This dramatically accelerates remediation compared to traditional black box tools.
Key Features
- Over 200 attack forms covering entire OWASP Top 10
- Advanced IAST sensor correlation for lower false positives
- CI/CD pipeline integration
- API scanning (REST, SOAP, GraphQL)
- Interactive attack replay
- Developer remediation guidance
- Full commercial support included
Contrast also offers integrated dynamic, static, software composition analysis (SCA), cloud security posture management (CSPM), and more in one unified platform.
2. Probely
Probely markets itself as a false-positive free DAST scanner built for continuous AppSec testing across the CI/CD pipeline.
It leverages smart request clustering and attack chaining to achieve more comprehensive coverage while eliminating inaccurate findings.
Key features
- Headless browser crawling for advanced JS site maps
- Minimal false positives via ML and runtime attack chaining
- Real-time security feedback via Slack, Jira, GitHub
- CI/CD integration with Jenkins, CircleCI, Travis CI
- API scanning for REST and GraphQL
- Unlimited testing – no IP restrictions
- Compliance reports (PCI DSS, ISO27001, GDPR)
Probely also offers turn-key managed DAST scans starting under $150/month for up to 4 targets.
3. IBM Application Security on Cloud
IBM Cloud Application Security Testing continuously tests web and API-based systems using DAST to identify vulnerabilities while providing guidance to fix issues neatly within your native IDE.
It combines DAST scans with interactive AST tools that enable devs to get context for each vulnerability found along with guided remediation.
Key capabilities:
- One click set up and deploy
- CI/CD integration across entire pipeline
- 150+ attack vectors covering OWASP Top 10
- Interactive AST for accelerated remediation
- API scanning for REST, SOAP and GraphQL
- Reporting for compliance (PCI, HIPAA, GDPR)
By leveraging Watson capabilities within the IBM Cloud, this DAST scanner also auto-tunes itself to your app landscape for optimized accuracy.
4. Rapid7 InsightAppSec
Rapid7 InsightAppSec provides dynamic scanning reinforced by expert research to identify vulnerabilities with low false positives.
It combines DAST scans with access to Rapid7‘s leading threat intelligence to tuned detections to real-world exposures gleaned from frontline incident response.
What makes InsightAppSec unique:
- Threat intelligence-powered scanning from frontline IR experts
- Broad API support including REST, SOAP, and GraphQL
- Two scan engines: One optimized for apps and one for APIs
- Zero-day attack capabilities
- Built-in malware scans during DASTPassive and active discovery for hidden attack surfaces
- Automatic validation of vulnerability exploitability
- Developer-oriented remediation guidance
Rapid7 also offers additional AppSec testing capabilities beyond DAST, including SCA, mobile app scans, and more.
5. Invicti Beyond
Beyond DAST combines dynamic scanning, interactive scanning, and manual assessments to provide comprehensive testing engineered to defeat modern defense evasion techniques.
It leverages multiple integrated engines (ZAP, SQLMap, XSS Joomla) to achieve broad coverage of common exposures.
Key DAST features
- Combines DAST, IAST and manual pen testing
- Broad language support – 6 languages
- REST, SOAP and GraphQL API scanning
- Manual configuration of authentication
- CI/CD integration
- Client-side attack support
- Anti-evasion techniques
- Compliance & regulatory reporting
As part of the Invicti suite, Beyond DAST can integrate scans with SCA, SAST security, and manual pen testing.
6. Checkmarx CxSAST
The Checkmarx one platform unifies SAST, SCA, and DAST testing capabilities for streamlined AppSec testing workflows. Developers get security feedback and guidance early while DAST scans find issues that make it production deployment.
Checkmarx leverages the robust SAST engine to accelerate DAST scan precision by integrating vulnerability Static AST results into Dynamic testing to eliminate false positives.
Why customers consistently rate Checkmarx DAST as an industry leader:
- Unified SAST, DAST and SCA testing
- Enriched DAST scanning with SAST vulnerability correlation
- Broad coverage beyond just OWASP Top 10
- Correlated findings across multiple scan types
- Capable API scanning feature set
- Low false positive rates
- Developer-focused remediation guidance
As part of the Checkmarx platform, CxSAST allows unified management of AppSec testing programs from one single dashboard.
7. ShiftLeft Scan
ShiftLeft Scan provides an innovative DAST solution that enables CI/CD pipeline security testing without the need for expertise in AppSec or even access to source code.
It features agentless scanning optimized for modern container and functions-as-a-service based architectures.
What sets ShiftLeft‘s DAST approach apart:
- Designed specifically for modern container, serverless, functions environments
- Agentless scanning integrates seamlessly into CI/CD
- Trainable DAST engine using AI/ML intelligence
- Captures attack context across entire kill chain
- Provides remediation guidance tailored for developers
- No source code required
ShiftLeft combines DAST scanning with runtime protections in a single platform to embed security within critical CI/CD pipelines.
Leading Open Source DAST Tools
Can’t budget for commercial dynamic scanners? Open source options provide a free alternative – with the right expertise.
8. Zed Attack Proxy (ZAP)
One of the most popular free web application scanners used by 500,000+ developers, ZAP offers comprehensive DAST capabilities powered by its active development community.
Why ZAP stands out from other open source scanners:
- Completely free and open source
- Actively maintained by a large open community
- Covers all major web vulnerability classes
- Provides penetration test reports summarizing findings
- Offers browser-driven exploratory security testing
- Easy integration into CI/CD pipeline
- Extensible via built-in marketplace of plug-ins
- Multi-language support beyond just English
The biggest downside vs commercial scanners is the need for AppSec expertise to configure custom scan policies and validate results.
9. SQLMap
This popular free hacking tool focuses specifically on detecting and exploiting SQL injection vulnerabilities in web apps as well as blind injection flaws that can disguise malicious database queries.
While limited to just SQLi testing, SQLMap offers more advanced evasion techniques and custom exploit chaining compared to commercial DAST solutions.
SQLMap‘s key strengths:
- Open source SQL injection detection tool
- Capable of advanced evasion to beat WAFs
- Identifies blind SQLi difficult to detect
- Built-in tampering and exploitation modules
- Broad database server support
- Ease of integration into CI pipelines
- Multi-threaded testing performance
For finding one of the most dangerous web flaws, SQLMap can’t be beaten for customization – but requires expert configuration for useful results.
How to Choose The Right DAST Tool
With so many capable DAST solutions to pick from, here is a step-by-step process for selecting the right tool:
Step 1: Define Requirements
Start by outlining your use cases, environment specifics, talent gaps, and key drivers motivating DAST adoption in the first place. Common requirements include:
- Supported languages/frameworks
- App environments (cloud vs. self-hosted)
- Skill level of personnel executing scans
- Integration with existing DevOps pipelines
- Flexible pricing models (self-service, managed scans, etc)
Step 2: Make a Shortlist
With requirements established, create a shortlist of vendors that seem to best align. Balance commercial and open source options based on available expertise.
Step 3: Request Demos & Quotes
Schedule demos and pricing quotes from your top choices. Most commercial vendors offer free pilots and demos. Focus demos on ease of setup/use, quality of findings, integration workflows, and overall satisfaction among peers.
Step 4: POC Final Solutions
Download trials or test freemium tiers of your top solutions. Work hands-on to get a feel for actual tool usability based on your own criteria. Submit support tickets during POCs to evaluate responsiveness.
Step 5: Perform Business & Technical Review
Compare solutions across both business and technical measures to score on fit. Business criteria may include total cost, vendor stability, etc. Technical focuses on coverage, accuracy, integrations.
Step 6: Select & Procure
With your evaluation complete, purchase your top choice tool. For commercial solutions, negotiate longer contracts that allow room to mature scanning programs maximizing your investment.
Integrating DAST Scanning
The whole point of DAST testing is to find exploitable vulnerabilities in running software. So optimal integration enables security tests on every build, commit or deploy incrementally across the entire pipeline.
Here are 3 tips for painless integration:
Utilize API access – Most AppSec tools provide API access to initiate and monitor scans programmatically. This avoids manual UI logins, letting pipelines handle testing flows.
Build DAST templates – Don’t reinvent wheel on scans. Centrally build and store base configurations, authentication macros, custom rules to import across apps.
Fail builds fast – Use DAST gates to abort commits or deployments the moment a high/critical vulnerability appears without manual triage. Fast failure provides instant security feedback developers understand.
The Case for Combining DAST Testing Approaches
While DAST capabilities have expanded enormously, its external perspective and simulated attacks make it just one piece of an effective AppSec program.
For comprehensive testing, DAST works best paired with complementary approaches:
DAST + SAST – Jointly assess apps from both outside-in and inside-out to find the broadest range of vulnerabilities throughout the SDLC.
DAST + IAST – Correlate dynamic findings with runtime application telemetry to eliminate false positives and speed remediation.
DAST + Manual Pen Testing – Expert human QA augments automated scanning with advanced techniques and business logic testing.
DAST + RASP – Runtime application protection builds on DAST results to actively protect apps from attacks in production.
An integrated AppSec platform combines DAST with multiple approaches for unified visibility, reporting and remediation flows across build, test and runtime.
Conclusion
DAST has quickly gone from nice-to-have to must-have for securing modern applications. As threats accelerate, its outside-in perspective offers assurance against externally executable vulnerabilities no amount of internal testing can replace.
This exhaustive guide reviewed what DAST is, how leading tools work, top solutions available and critical intricacies of successful program design.
The key is architecting a pragmatic program combining DAST testing tailored to your organization‘s risk profile, AppSec maturity and cloud adoption trends.
With the insights provided throughout this deep dive, you have all the knowledge needed to pick, procure and integrate the ideal DAST scanner meeting the unique needs of your SDLC, developers and attack surface.
