The Web Application Hacker’s Handbook Discovering and Exploiting Security Flaws

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Chapter 11 

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Attacking Application Logic

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3. What steps could you take to probe a login function for fail-open condi-

tions? (Describe as many different tests as you can think of.)

4. A banking application implements a multistage login mechanism that is

intended to be highly robust. At the first stage, the user enters a user-

name and password. At the second stage, the user enters the changing

value on a physical token that they possess, and the original username

is resubmitted in a hidden form field.

What logic flaw should you immediately check for?

5. You are probing an application for common categories of vulnerability

by submitting crafted input. Frequently, the application returns verbose

error messages containing debugging information. Occasionally, these

messages relate to errors generated by other users. When this happens,

you are unable to reproduce the behavior a second time. What logic

flaw may this indicate, and how should you proceed?