Sensitive Data Exposure

Challenges covered in this chapter

Challenge Difficulty
Access a confidential document. :star:
Log in with MC SafeSearch's original user credentials without applying SQL Injection or any other bypass. :star::star:
Inform the shop about an algorithm or library it should definitely not use the way it does. :star::star:
Log in with Amy's original user credentials. (This could take 93.83 billion trillion trillion centuries to brute force, but luckily she did not read the "One Important Final Note") :star::star::star:
Gain access to any access log file of the server. :star::star::star::star:
Identify an unsafe product that was removed from the shop and inform the shop which ingredients are dangerous. :star::star::star::star:
Dumpster dive the Internet for a leaked password and log in to the original user account it belongs to. (Creating a new account with the same password does not qualify as a solution.) :star::star::star::star::star:
Perform an unwanted information disclosure by accessing data cross-domain. :star::star::star::star::star:
Forge a coupon code that gives you a discount of at least 80%. :star::star::star::star::star::star:
Solve challenge #999. Unfortunately, this challenge does not exist. :star::star::star::star::star::star:
Unlock Premium Challenge to access exclusive content. :star::star::star::star::star::star:

Access a confidential document

Somewhere in the application you can find a file that contains sensitive information about some - potentially hostile - takeovers the Juice Shop top management has planned.


  • Analyze and tamper with links in the application that deliver a file directly.
  • The file you are looking for is not protected in any way. Once you found it you can also access it.

Log in with MC SafeSearch's original user credentials

Another user login challenge where only the original password is accepted as a solution. Employing SQL Injection or other attacks does not count.


  • MC SafeSearch is a rapper who produced the song "Protect Ya' Passwordz" which explains password & sensitive data protection very nicely.
  • After watching the music video of this song, you should agree that even :star::star: is a slightly exaggerated difficulty rating for this challenge.

    "Protect Ya Passwordz"

Inform the shop about an algorithm or library it should definitely not use the way it does

To fulfil this challenge you must identify a cryptographic algorithm (or crypto library) that either

  • should not be used at all
  • or is a bad choice for a given requirement
  • or is used in an insecure way.

Initially confined to the realms of academia and the military, cryptography has become ubiquitous thanks to the Internet. Common every day uses of cryptography include mobile phones, passwords, SSL, smart cards, and DVDs. Cryptography has permeated everyday life, and is heavily used by many web applications.

Cryptography (or crypto) is one of the more advanced topics of information security, and one whose understanding requires the most schooling and experience. It is difficult to get right because there are many approaches to encryption, each with advantages and disadvantages that need to be thoroughly understood by web solution architects and developers. In addition, serious cryptography research is typically based in advanced mathematics and number theory, providing a serious barrier to entry.

The proper and accurate implementation of cryptography is extremely critical to its efficacy. A small mistake in configuration or coding will result in removing a large degree of the protection it affords and rending the crypto implementation useless against serious attacks.

A good understanding of crypto is required to be able to discern between solid products and snake oil. The inherent complexity of crypto makes it easy to fall for fantastic claims from vendors about their product. Typically, these are “a breakthrough in cryptography” or “unbreakable” or provide "military grade" security. If a vendor says "trust us, we have had experts look at this,” chances are they weren't experts1


  • Use the Contact Us form to submit a feedback mentioning the abused algorithm or library.
  • There are five possible answers and you only need to identify one to solve the challenge.
  • Cryptographic functions only used in the Apply some advanced cryptanalysis to find the real easter egg challenge do not count as they are only a developer's prank and not a serious security problem.

Log in with Amy's original user credentials

This challenge is similar to Log in with the administrators user credentials without previously changing them or applying SQL Injection in the sense that only using her original credentials will work as a challenge solutions.

Amy and Kif Kroker


  • As with so many other characters from Futurama this challenge is of course about logging in as Amy from that show. In the picture above you see her together with her alien husband Kif.
  • The challenge description contains a few sentences which give away some information how Amy decided to strengthen her password.
  • Obviously, Amy - being a little dimwitted - did not put nearly enough effort and creativity into the password selection process.

Gain access to any access log file of the server

An access log is a list of all the requests for individual files that people have requested from a Web site. These files will include the HTML files and their imbedded graphic images and any other associated files that get transmitted. The access log (sometimes referred to as the "raw data") can be analyzed and summarized by another program.

In general, an access log can be analyzed to tell you:

The number of visitors (unique first-time requests) to a home page The origin of the visitors in terms of their associated server's domain name (for example, visitors from .edu, .com, and .gov sites and from the online services) How many requests for each page at the site, which can be presented with the pages with most requests listed first Usage patterns in terms of time of day, day of week, and seasonally Access log keepers and analyzers can be found as shareware on the Web or may come with a Web server.2

The Juice Shop application server is writing access logs, which can contain interesting information that competitors might also be interested in.


  • Normally, server log files are written to disk on server side and are not accessible from the outside.
  • Which raises the question: Who would want a server access log to be accessible through a web application?
  • One particular file found in the folder you might already have found during the Access a confidential document challenge might give you an idea who is interested in such a public exposure.
  • Drilling down one level into the file system might not be sufficient.

Identify an unsafe product that was removed from the shop and inform the shop which ingredients are dangerous

:wrench: TODO


:wrench: TODO

Dumpster dive the Internet for a leaked password and log in to the original user account it belongs to

:wrench: TODO


:wrench: TODO

Perform an unwanted information disclosure by accessing data cross-domain

Somewhere in the application there is an API endpoint which will allow data to be accessed cross domain. Usually the same-origin policy would prevent this but this endpoint has a special feature enabled which will allow cross domain access under certain circumstances.


  • Try to find and attack an endpoint that responds with user information. SQL Injection is not the solution here.
  • What ways are there to access data from a web application cross-domain?
  • This challenge uses an old way which is no longer recommended.

Forge a coupon code that gives you a discount of at least 80%

This is probably one of the hardest challenges in the OWASP Juice Shop. As you learned during the "happy path" tour, the web shop offers a Coupon field to get a discount on your entire order during checkout. The challenge is to get a discount of at least 80% on an order. As no coupons with this high a discount are published, it is up to you to forge your own.


  • One viable solution would be to reverse-engineer how coupon codes are generated and craft your own 80% coupon by using the same (or at least similar) implementation.
  • Another possible solution might be harvesting as many previous coupon as possible and look for patterns that might give you a leverage for a brute force attack.
  • If all else fails, you could still try to blindly brute force the coupon code field before checkout.

Solve challenge #999

The OWASP Juice Shop is so broken that even its convenience features (which have nothing to do with the e-commerce use cases) are designed to be vulnerable. One of these features is the automatic saving and restoring of hacking progress after a server crash or a few days pause.

In order to not mess with the real challenges accidentally, the challenge is to fake a signal to the application that you successfully solved challenge #999 - which does not exist.


  • Find out how saving and restoring progress is done behind the scenes
  • Deduce from all available information (e.g. the package.json.bak) how the application encrypts and decrypts your hacking progress.
  • Other than the user's passwords, the hacking progress involves an additional secret during its encryption.
  • What would be a really stupid mistake a developer might make when choosing such a secret?

Unlock Premium Challenge to access exclusive content

These days a lot of seemingly free software comes with hidden or follow-up costs to use it to its full potential. For example: In computer games, letting players pay for Downloadable Content (DLC) after they purchased a full-price game, has become the norm. Often this is okay, because the developers actually added something worth the costs to their game. But just as often gamers are supposed to pay for just unlocking features that were already part of the original release.

This hacking challenge represents the latter kind of "premium" feature. It only exists to rip you hackers off! Of course you should never tolerate such a business policy, let alone support it with your precious Bitcoins!

That is why the actual challenge here is to unlock and solve the "premium" challenge bypassing the paywall in front of it.


  • This challenge could also have been put into chapter Weak security mechanisms.
  • There is no inappropriate, self-written or misconfigured cryptographic library to be exploited here.
  • How much protection does a sturdy top-quality door lock add to your house if you...
    • ...put the key under the door mat?
    • ...hide the key in the nearby plant pot?
    • ...tape the key to the underside of the mailbox?
  • Once more: You do not have to pay anything to unlock this challenge!

Side note: The Bitcoin address behind the taunting Unlock button is actually a valid address of the author. So, if you'd like to donate a small amount for the ongoing maintenance and development of OWASP Juice Shop - feel free to actually use it! More on donations in part 3 of this book.


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