What is the difference between static analysis and dynamic analysis?

Question

---

What is the difference between static analysis and dynamic analysis in terms of cyber security?

Answer 1

Static analysis means "read the source code and try to identify failures". For security, static analysis tools try to find security holes in the code, which are then presumably fixed before the code is released for production use.

Dynamic analysis means "watch the actual execution of the application to identify failures (e.g, deref null pointers, array access past the end of an array, re-use of dynamically allocated block without first freeing it, ...". Done during application development and debugging, it can find errors which are then presumably fixed before the code is released for production. Done during production execution, it may detect errors the software is about to make, and prevent those errors (e.g., don't actually do the deref, report an application error instead), at the price of considerably higher execution costs because of the intrusive nature of dynamic analysis.

Each has different strengths and weaknesses. Both techniques suffer from the Turing-induced inability to reason about software activities completely. Most of these tools have failings where they miss problems, or report problems that are not real. Usually these tools try to avoid reporting false positives, because people won't use tools the produce lots of such errors. Limiting the false positives tends to limit reporting of real errors too, so you can't be sure that a clean report means "no problems".

Answer 2

Both are types of software testing that are looking for un-unintended security vulnerabilities. As such they are separate from the unit or system testing which is focused on verifying expected outcomes or requirements

Static analysis (SAST) works at the code level. It is code scanning and looks for patterns of know vulnerabilities or poor coding practice. For instance scanning code to discover the use of insecure libraries.

Dynamic analysis (DAST) works at the compiled system level. It scans built systems looking for known vulnerabilities. For instance, scanning a web application via its front end to find cross-site scripting vulnerabilities.

Both are generally used during the SDLC pre-release. SAST tends to be to the left of DAST and can pick up issues earlier, however, neither are fully effective at picking up all issues, and both are also prone to false positives.

Answer 3

Static analysis and dynamic analysis are two distinct approaches used in software testing and security assessment. Here's an explanation of the differences between these two methods:

1. Static Analysis:

   • Static analysis is a technique that examines the source code, byte code, or binary of a software application without executing it.
   • It involves analyzing the code structure, syntax, and dependencies to identify potential defects, vulnerabilities, and coding errors.
   • Static analysis tools analyze the code for various properties, such as coding standards compliance, potential security vulnerabilities, memory leaks, and performance optimizations.
   • It can provide insights into potential issues early in the development process and is commonly used during code review or as part of the build process.
   • Static analysis can be automated and performed using specialized tools, and it helps developers identify and fix issues before the software is executed.

2. Dynamic Analysis:

   • Dynamic analysis involves analyzing the behavior of a software application while it is running or being executed.
   • It requires executing the software with various inputs or test cases to observe its behavior, performance, and interactions with the system.
   • Dynamic analysis tools monitor and capture runtime information such as memory usage, CPU utilization, network traffic, and system calls.
   • It helps identify runtime errors, security vulnerabilities, performance bottlenecks, and other issues that may not be apparent during static analysis.
   • Dynamic analysis can be useful for uncovering issues related to input validation, memory corruption, concurrency, resource leaks, and runtime exceptions.
   • It is commonly used in functional testing, security testing, and performance testing to assess the software's behavior under different scenarios.

In summary, static analysis involves examining the code without executing it, focusing on code structure and potential issues in the source code. Dynamic analysis, on the other hand, involves executing the software and analyzing its behavior in runtime, aiming to uncover issues that manifest during execution. Both approaches have their strengths and are often used in combination to achieve comprehensive software testing and security assessment.