Modern websites are a complex mix of content, resources, and JavaScript that creates a rich, dynamic user experience. All of this content is loaded and executed by the browser on the user’s laptop or mobile device, which improves performance and responsiveness. However, this also creates an attack surface for hackers to inject and execute malicious scripts from alternate domains. These scripts can be used to execute cross-site scripting (XSS) attacks, or digital skimming attacks such as Magecart that result in the theft of personal data from your website.
In addition, content security policy is a useful tool in the fight against unauthorized shadow code that plagues web applications. Shadow code is typically introduced via scripts from open source libraries or third-parties that make their way onto a site without formal approvals or security validation.
Because shadow code often runs on the client-side browser, it cannot be seen or controlled using server-side security tools. This leaves an entry point for cybercriminals to inject malicious scripts that skim user data. Client-side attacks, such as digital skimming, formjacking and Magecart, can lead to data breaches or compliance penalties.
CSP script-src directive can be used to restrict the domains from where scripts can be loaded. This ensures that scripts are only loaded from known good domains, reducing the risk of shadow code injections on the website. Additionally, the connect-src directive can be used to restrict network communication with unknown domains, which can stop a malicious script from communicating with its command and control (C2) server and thus limit its ability to cause harm.