Cross-site request forgeries (“XSRF”) can be prevented using a client-side plugin on a client computer. The client computer accesses a content provided by a third party host via a network and generates a request to a web application as directed by the content. The client-side plugin determines whether the request is associated with suspicious activities based on the content, a source of the request and a list of approved hosts associated with the target host. In response to a determination that the request is associated with suspicious activities, the plugin removes authentication credentials from the request and sends the request to the web application.