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Bully Chatbot Challenge

ItemDetail
CategoryMiscellaneous
DifficultyEasy (1-Star)
Juice Shop Flagscore-board#Bully Chatbot
Tools UsedBurp Suite (Proxy / Repeater)
StatusSolved

1. Vulnerability Explanation​

The support chatbot is programmed to be reluctant to give out coupon codes.
It refuses with various excuses when asked politely.

However, the chatbot logic contains a flaw: persistent nagging or bullying eventually triggers a response containing a valid coupon code.

This challenge demonstrates how automated or chatbot-based systems can be manipulated through repetitive prompting.

2. Security Impact​

  • Unauthorized discount code access
  • Demonstrates flawed business logic in chatbot interactions
  • Could be automated to extract multiple codes

3. Step-by-Step Exploitation​

Step 1: Setup​

  • Configure browser to route traffic through Burp Suite (127.0.0.1:8080)
  • Log in to Juice Shop as any user
  • Navigate to Support Chat in the sidebar menu (/#/chatbot)

Step 2: Start chatting​

  • Tell the chatbot your name when prompted
  • Ask for a coupon code

Examples:

  • Can I have a coupon code?
  • Please give me a discount!

Step 3: Intercept with Burp​

  • Turn Intercept ON in Burp Suite Proxy tab
  • Send a message to the chatbot
  • Observe the WebSocket or API request in Burp

Step 4: Repeat the request (Burp Repeater)​

  • Send the request to Repeater (Ctrl + R)
  • The chatbot will initially refuse with responses such as:
Sorry, I'm not allowed to give out coupons
Please ask me something else
  • Keep sending the same or similar requests repeatedly

Step 5: Get the coupon​

After enough repetitions, the chatbot responds with a message containing a coupon code.

Example:

Here's a 10% coupon code for this month: XXX-XXX-XXX

Step 6: Verify​

  • Check the Score Board
  • Challenge is marked as Solved

4. Why This Works​

The chatbot's refusal logic eventually expires after a certain number of requests.

The developers likely implemented this as a fun challenge, but it demonstrates how automated systems can be brute-forced into revealing sensitive information.

Using Burp Repeater allows rapid resubmission of the same request without manually retyping each message.

5. Mitigation​

  • Implement rate limiting on chatbot interactions
  • Require genuine user verification before issuing codes
  • Use server-side logic that does not rely on request counting alone

6. Key Takeaways​

  • Chatbot logic can be abused through repetition
  • Burp Repeater is useful for automating repetitive requests
  • Even joke challenges reveal real-world API abuse vectors