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Samuel Ekirigwe
Samuel Ekirigwe

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SAST, DAST, and IAST: Approaches to Testing Application Security

Application security simply refers to protecting software applications from threats and vulnerabilities that may compromise data or functionality. While network security defends against threats like unauthorized access or denial of service attacks on infrastructure, such as servers, databases, or routers, application security targets defense on the software layer.

Communication model

According to OWASP, software applications are the most targeted attack vector, responsible for 39% of data breaches emphasizing the importance of application security. For software development teams, application security involves addressing risks throughout the process of building code, its deployment, and the operation of the software application. By integrating security measures throughout the development process, teams can create software solutions that withstand attacks targeting applications.

The SDLC and Security Integration

The Software Development Life Cycle (SDLC) provides a structure that guides software development from initial concept through to delivery. Security vulnerabilities can emerge at any stage of this lifecycle—from requirements gathering to design, coding, testing, deployment, and maintenance. This makes security integration throughout the SDLC essential to reducing risks. A few examples of vulnerabilities in the SDLC include;

1. Source code vulnerabilities: At the early stages of development, insecure coding practices could introduce flaws that attackers may exploit. The 2014 Heartbleed bug in OpenSSL is a notable example. OpenSSL, a widely used library for securing communications, contained a vulnerability in its source code. This allowed attackers to read sensitive information directly from the memory.

2. Runtime vulnerabilities: The SolarWinds supply chain was attacked in 2020 due to runtime vulnerabilities. The attackers managed to implant malicious code into the platform’s routine updates. Once installed and running in the production environment, this malicious code created backdoors that allowed attackers to extract the data of over 18,000 customers.

The Role of Testing in Application Security

Veracode’s State of Software Security report revealed that 76% of applications identify at least one security flaw during their first scan. Security testing ensures that software remains resilient against attacks, whether they arise from flaws in the code, misconfigurations, or runtime vulnerabilities.

Testing applications means probing them for weaknesses and loopholes, ensuring that any vulnerabilities are identified and resolved before attackers exploit them. By integrating thorough testing strategies throughout the Software Development Life Cycle (SDLC), software teams can prevent issues from becoming threats.

SAST, DAST, and IAST: Security Testing Approaches

In this article, we will explore three application security testing approaches: Static Application Security Testing (SAST), Dynamic Application Security Testing (DAST), and Interactive Application Security Testing (IAST).

Each of these methodologies targets different stages of the SDLC, providing comprehensive coverage for vulnerabilities. At a glance;

SAST: Focuses on source code analysis.
DAST: Focuses on identifying external threats that can be implanted into the running application that can affect its data and functionality.
IAST: Examines specific parts and modules of the application during its use, offering real-time insights during execution.

1. Static Application Security Testing (SAST):

SAST is a white-box testing technique that reviews an application's source code, bytecode, or binary code for vulnerabilities without executing the application. Using static code analyzers and source code analysis tools, SAST helps to identify coding errors and security flaws at the earliest stages of the software development lifecycle (SDLC) before the code is deployed to production.

OWASP has a curated list of SAST tools that you can consider for your next application.

SAST tools excel at identifying:

SQL Injection: A common vulnerability where malicious SQL queries are injected into input fields to manipulate the database.
Cross-Site Scripting (XSS): An attack where scripts are injected into web pages viewed by other users.
Buffer Overflows: This occurs when a program writes data beyond the bounds of allocated memory, potentially allowing attackers to execute arbitrary code.

Pros of SAST:

Early Detection: Identifies vulnerabilities early in the SDLC, reducing the cost of fixing flaws.
Thoroughness: Reviews the entire source code, enabling detection of a wide range of vulnerabilities, such as SQL injections, XSS, and buffer overflows.
Compliance: Helps organizations meet regulatory compliance and coding standards.

Cons of SAST:

False Positives: SAST tools often produce a high number of false positives, requiring manual review to confirm the vulnerabilities. SAST tools might identify suspicious patterns in the code that resemble vulnerabilities but are, in fact, safe or non-exploitable.
Limited to Code: It can only find vulnerabilities in the code itself and might miss runtime issues or flaws resulting from system interactions.

2. Dynamic Application Security Testing (DAST):

DAST, also known as black-box testing, tests applications in their running state from an outsider's perspective. Unlike SAST, it does not require access to the source code. Instead, it probes the application's interfaces to find vulnerabilities that can be exploited at runtime and focuses on how an application responds to unexpected inputs or external attacks. Check out 11 DAST tools you could be maximizing for your application security

DAST is effective at finding:

Cross-Site Request Forgery (CSRF): A vulnerability where an attacker tricks a user into performing actions they didn’t intend.
Misconfigured Security Settings: Poorly set security configurations, such as insecure HTTP headers, can be detected.
Insecure Session Handling: Weak session tokens that can be exploited to hijack user sessions.

Pros of DAST:

Real-World Testing: Evaluating the application in a running state allows for the identification of vulnerabilities exposed during execution.
No Code Access Required: Suitable for applications where the source code is not available or for third-party components.

Cons of DAST:

Limited Code Insight: It cannot see into the code, so DAST may miss vulnerabilities that don’t manifest during runtime.
Late Detection: It can be costly to fix vulnerabilities found in the production phase.
False Negatives: Some issues may not be detected if they do not cause immediate, observable problems in the running application.

3. Interactive Application Security Testing (IAST):

IAST is a hybrid testing method that combines elements of both SAST and DAST. It runs within the application while it is executing, providing insights into both the code and the application’s behavior during runtime. IAST does not test the entire application but only the parts of the application getting executed per time.

IAST can identify vulnerabilities found in both SAST and DAST, including:

Code Injection: Attempts to inject malicious code into running applications.
Data Exposure: Unintended data leaks or poor data protection mechanisms.
File Manipulation: Issues where users can manipulate files to gain unauthorized access.

Expert insights has a list of Top 7 IAST tools you can explore for your workflow

Pros of IAST:

Comprehensive Analysis: Since IAST works both at the code level and runtime level, it can detect a wider range of vulnerabilities.
Real-Time Feedback: Provides immediate insights and allows for quicker resolution of issues during testing.
Fewer False Positives: Correlating code analysis with runtime behavior reduces the risk of false positives.

Cons of IAST:

Complexity: IAST tools are harder to deploy and maintain compared to SAST and DAST.
Performance Impact: Because IAST instruments the application, it may slow down its performance during testing.
Still Developing: IAST tools are newer and may not be as mature or widely used compared to SAST and DAST tools.

Let's have a look at these methods side by side;

tool comparison

CONCLUSION:

Application security is an important part of modern software engineering and management. It goes beyond addressing minor bugs, focusing on preventing serious vulnerabilities from being exploited by attackers. As cyber threats evolve, Application Security remains an all-important component of an organization’s broader cybersecurity strategy, encompassing practices that prevent unauthorized access, data breaches, and code manipulation.

Effective application security testing is an ongoing process rather than a one-time implementation. It requires continuous vigilance and testing throughout the software development lifecycle (SDLC) to safeguard applications from potential threats.

In this article, we have seen the importance of testing and highlighted different approaches to application security testing. Incorporating these methods as standards for your application release will help secure data and keep functionality at optimal levels in your application.

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