Object-Oriented Software Engineering

This is an archived version of https://www.jhu-oose.com that I (Leandro Facchinetti) developed when teaching the course in the Fall of 2019. Some of the links may be broken.

Assignment 8: Security

Working on the Assignment

SQL Injection

20 points

  1. Disable the protection for SQL Injection in the delete() method of the ItemsRepository class. Follow the same procedure we did in lecture for the update() method.

    How did you change the code to do that?

  2. Forge a request in Postman to explore the vulnerability. Remember that the identifier is in the URL, so you want to create a request just like “Mark item as done”, except with something other than {{itemIdentifier}} in the URL. Come up with something such that if the SQL Injection succeeded then all items would be deleted from the database in a single request. Think about what you’d have to append to DELETE FROM items WHERE identifier = to make that happen.

    What did you put in place of {{itemIdentifier}} in the URL?

  3. But that doesn’t work. Why?

Cross-Site Scripting (XSS)

20 points

  1. Consider the TODOOSE code base at the xss branch, in which the XSS protection in React has been disabled. Write an item description which renders a button that, when clicked, simulates a click on every checkbox on the page, marking all items as done and removing them from the database.

  2. After the lecture I learned that there are ways to run JavaScript even without user interaction—that is, without having to trick the user into clicking a button, for example! Write an item description that explores this vulnerability and causes an alert('Spooky') to show up as soon as the user opens TODOOSE on the browser.

User Management


25 points

In lecture we talked about how it’s insecure to store passwords in plaintext on the database, and how to use bcrypt to fix this. Carry out the implementation, starting with the TODOOSE code base at the user-management branch. You only need to work on the server—the tests may be failing and the client may be broken.


25 points

I found this library and it gave me an idea: Instead of running bcrypt on the server, how about we run it on the client? On user signup and user login, the browser could run bcrypt on the password and pass the resulting string to the server. The server wouldn’t run bcrypt at all.

Do you think this would be as secure as the implementation above? Why?


10 points

Read the notes on refactoring. Revisit your answer to the Technology part of Assignment 3. Discuss at least two refactorings from the catalog that you performed even though you didn’t know their names: What are they? Where did you use them? And so forth.


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