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Application Review

Learn how to review a mature application effectively by defining a pragmatic, flexible, and results-oriented process that includes preassessment, code review, and remediation support. Discover various design review approaches and code auditing strategies to identify and address flaws in the application. Increase your understanding of the code through iterative reviews and utilize auditing tools for thorough analysis.

jenniferdjackson
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Application Review

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  1. Application Review • Reviewing a mature (possibly complete) application • A daunting task if the system is large • And often you know little about it • Maybe you performed a design review • Maybe you read design review docs • Maybe less than that • How do you get started?

  2. Need to Define a Process • Don’t just dive into the code • Process should be: • Pragmatic • Flexible • Results oriented • Will require code review • Which is a skill one must develop

  3. Review Process Outline • Preassessment • Get high level view of system • Application review • Design review, code review, maybe live testing • Documentation and analysis • Remediation support • Help them fix the problems • May need to iterate

  4. Reviewing the Application • You start off knowing little about the code • You end up knowing a lot more • You’ll probably find the deepest problems related to logic after you understand things • A design review gets you deeper quicker • So worth doing, if not already done • The application review will be an iterative process

  5. General Approaches To Design Reviews • Top-down • Start with high level knowledge, gradually go deeper • Bottom-up • Look at code details first, build model of overall system as you go • Hybrid • Switch back and forth, as useful

  6. Code Auditing Strategies • Code comprehension (CC) strategies • Analyze source code to find vulnerabilities and increase understanding • Candidate point (CP) strategies • Create list of potential issues and look for them in code • Design generalization (DG) strategies • Flexibly build model of design to look for high and medium level flaws

  7. Some Example Strategies • Trace malicious input (CC) • Trace paths of data/control from points where attackers can inject bad stuff • Analyze a module (CC) • Choose one module and understand it • Simple lexical candidate points (CP) • Look for text patterns (e.g., strcpy()) • Design conformity check (DG) • Determine how well code matches design

  8. Guidelines for Auditing Code • Perform flow analysis carefully within functions you examine • Re-read code you’ve examined • Desk check important algorithms • Use test cases for important algorithms • Using real system or desk checking • Choosing inputs carefully

  9. Useful Auditing Tools • Source code navigators • Debuggers • Binary navigation tools • Fuzz-testing tools • Automates testing of range of important values

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