Web application security - the fast guide 1.1 | Page 105

Chapter 5 - Attack Execution the client
P a g e | 105
Collected information are the pay pal credentials that can be used directly to pay
for purchases.
5.16 Altering hidden fields
This type of attack focus on altering data and affecting data integrity it depends
on changing the information passed as part of request as a hidden field.
Attack requirement:
A. One or more parameter is passed as hidden field
B. The server is not checking those parameters before usage
Attack process
A. Using a proxy capture the request.
B. Alter the hidden field as required
C. Release the altered request
Example:
POST /buy/25/buy.php?prod=55 HTTP/1.1
Host: mazadme.com
Content-Type: application/x-www-form-urlencoded
Content-Length: 20
q=3&p=300
the previous listing represent a request sent from a form having the product id
as part of the request header in time where the quantity (q) and the price (p) is
sent as hidden value in the request body.
A. Using a proxy tool like (Burp Proxy) setup the proxy to intercept requests
sent by your browser.
B. Using intercept tab edit the sent header and product price (p) as required.