Method and System for Automatically Verifying an Appropriate Use of a Security Token for Avoiding Cross Site Request Forgery (CSRF) Attacks

Abstract

A method and system for automatically verifying an appropriate use of a security token for avoiding Cross Site Request Forgery (CSRF) attacks is disclosed. 

Description

A Cross Site Request Forgery (CSRF) is a security attack where a user’s browser or a web application automatically transmits commands to a website without the user’s knowledge.  To protect the user from the CSRF security attack, the website must ensure that any malicious code or a hacker does not generate these commands received from the user’s browser.  One of the techniques to achieve this is to use a security token (also known as a crumb) along with a cookie to identify or authenticate the commands.  In addition, it is important to verify that the security token is used in an appropriate manner to avoid the CSRF security attack.

Disclosed is a method and system for automatically verifying an appropriate use of the security token for avoiding CSRF security attacks.  A security token checker tool is used for automating the verification process that works as a proxy and resides between a client browser and a server.  In a scenario, a Hypertext Transfer Protocol (HTTP) forward proxy code may be modified for creating the security token checker tool.  Thereafter, the security token checker tool processes all commands or requests sent by the client browser to the server and responses sent by the server to the client browser.  The requests and responses are validated to certify that the security token check is working properly on the server.  For this purpose, the security token checker tool performs two validations on the requests and the responses.

A first validation ensures that the request sent from the client browser to the server is compulsorily using the security token as a parameter to validate its request origin.  The request sent from the client browser to the server is used as a base request for generating three more invalid requests by tampering the security token.  These three invalid requests must then generate an error response.

A second validation initially ensures that the server honors the security token sent by the client browser.  Thereafter, the second validation processes the three invalid requests and ensures an error message in a response generated by the server.

Figure

The figure depicts the three invalid requests generated by the security token checker tool by tampering the security token during the first validation.  For generating the first invalid request, the security token checker tool removes a security token parameter from a request thereby ensuring a case that a property has used the security token parameter.  Similarly, for generating the second invalid request, the security token checker tool sends the security token value as null in new request.  This modification ensures that t...