Insecure Direct Object References¶
What is Parameter Tampering?¶
Parameter tampering is a form of Web-based attack in which certain parameters in the Uniform Resource Locator (URL) or Web page form field data entered by a user are changed without that user's authorization. This points the browser to a link, page or site other than the one the user intends (although it may look exactly the same to the casual observer).
Parameter tampering can be employed by criminals and identity thieves to surreptitiously obtain personal or business information about the user. Countermeasures specific to the prevention of parameter tampering involve the validation of all parameters to ensure that they conform to standards concerning minimum and maximum allowable length, allowable numeric range, allowable character sequences and patterns, whether or not the parameter is actually required to conduct the transaction in question, and whether or not null is allowed.
Parameter Tampering Example¶
Here is a common URL in a web application.
A malicious user could modify the
account parameter trying to view another person's account details.
Manipulating a hidden field parameter is another common attack.
<input type="hidden" id="product-1" name="cost" **value="70.00"**>
Another malicious user could modify the
value parameter in an e-commerce web page and take advantage of this attack.
How to prevent Parameter Tampering¶
Access control check¶
The application should perform an access control check to ensure the user is authorized for the request object or service:
- Use instance-based security features, used for specifying access control lists applicable to domain objects.
- On render time, store data values in session and on submit, check the received values with stored values.
- Check in the database that the data sent by the user is genuine. For example, if the user sends an account number, perform a JOIN operation between
USERtables to check that the given account belongs to the user. In most cases, this requires a JOIN operation between multiple tables.
Always check user input before using it because malicious input is the root cause of this type of threat. Validation must be performed on the server side, since client-side validation cannot guarantee avoiding malicious input.
Use Hdiv's integrity validation¶
Hdiv flow control ensures data integrity, nullifying this risk
Hdiv’s web information flow control system controls all data generated at the server side ensuring its integrity. An additional option makes it possible to ensure the confidentiality of data generated at the server side, avoiding exposure of critical data such as credit cards, etc. Hdiv guarantees integrity (no modification) of all data generated by the server which should not be modified by the client (links, hidden fields, combo values, radio buttons, etc.). Thanks to this feature, Hdiv helps to eliminate most vulnerabilities which can be attacked by parameter tampering.