Computing system for cross-site request forgery attack protection

A method executed by a processor of a server computing device, comprising:

• receiving, by a server agent application being executed by the processor, a uniform resource locator (URL) from a client agent application executing on a client computing device, the URL including an identifier for a graphical resource that is to be provided by a third-party application;
• responsive to determining, by the server agent application and based upon the URL, that the graphical resource is to be provided by the third-party application, causing, by the server agent application, an intermediate application to be launched that is executed by the processor;
• requesting, by the intermediate application, a webpage from the third-party application, the webpage including a security token for a user session between the client agent application and the third-party application;
• responsive to receiving the webpage from the third-party application, extracting, by the intermediate application, the security token from the webpage;
• constructing, by the intermediate application, a modified URL based upon the URL and the security token;
• transmitting, by the intermediate application, the modified URL to the third-party application, wherein the third-party application generates the graphical resource based upon the modified URL;
• receiving, by the intermediate application, the graphical resource;
• removing, by the intermediate application, the security token from the graphical resource;
• and
• transmitting, by the intermediate application, the graphical resource to the client agent application, wherein the client agent application presents the graphical resource on a display of the client computing device.

A non-transitory computer-readable storage medium comprising instructions that, when executed by a processor of a client computing device, cause the processor to perform acts comprising:

• receiving, by a server agent application being executed by the processor, a uniform resource locator (URL) from a client agent application executing on a client computing device, the URL including an identifier for a graphical resource that is to be provided by a third-party application;
• responsive to determining, by the server agent application and based upon the URL, that the graphical resource is to be provided by the third-party application, causing, by the server agent application, an intermediate application to be launched that is executed by the processor;
• requesting, by the intermediate application, a webpage from the third-party application, the webpage including a security token for a user session between the client agent application and the third-party application;
• responsive to receiving the webpage from the third-party application, extracting, by the intermediate application, the security token from the webpage;
• constructing, by the intermediate application, a modified URL based upon the URL and the security token;
• transmitting, by the intermediate application, the modified URL to the third-party application, wherein the third-party application retrieves the graphical resource based upon the modified URL;
• receiving, by the intermediate application, the graphical resource;
• removing, by the intermediate application, the security token from the graphical resource;
• and
• transmitting, by the intermediate application, the graphical resource to the client agent application, wherein the client agent application presents the graphical resource on a display of the client computing device.