Based on a presentation at LocoMocoSec, the following two policies can be used to apply a strict policy: When default-src or script-src* directives are active, CSP by default disables any JavaScript code placed inline in the HTML source, such as this: The inline code can be moved to a separate JavaScript file and the code in the page becomes: With app.js containing the var foo = "314" code. In C, why limit || and && to evaluate to booleans? It feels wrong needing to turn off such a powerful security feature. This list allows for granular control of the source of scripts, images, files, etc. The CSP policy is denying the user's browser permission to load anything else. A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges. I'm looking for a good way to implement a relatively strong Content-Security-Policy header for my ASP.NET WebForms application. A website can declare multiple CSP headers, also mixing enforcement and report-only ones. Allows the usage of inline scripts or styles. Google went ahead and set up a guide to adopt a strict CSP based on nonces. This pattern can be used for example to run a strict Report-Only policy (to get many violation reports), while having a looser enforced policy (to avoid breaking legitimate site functionality). Passive mixed content is displayed by default, but users can set a preference to block this type of content, as well. For more details, check out strict-dynamic usage. The CSP policy only applies to content found after the meta tag is processed, so you should keep it towards the top of your document, or at least before any dynamically generated content. In May 2017[23] one more method was published to bypass CSP using web application frameworks code. If the Content-Security-Policy header is present in the server response, a compliant client enforces the declarative allowlist policy. Dont have an Intel account? My team operates across all Digital areas of MOJ, including Criminal Injuries Compensations Authority, Office of the Public Guardian and HM Prison and Probation Service, to help support them in creating The default-src directive restricts what URLs resources can be fetched from the document that set the Content-Security-Policy header. Asking for help, clarification, or responding to other answers. The meta support is handy when you can't set a HTTP response header, but in most cases using a HTTP response header is a stronger approach. You can easily search the entire Intel.com site in several ways. We basically identified what we use and don't use. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. In order to ensure backward compatibility, use the 2 directives in conjunction. With this minimum configuration, your HTML is allowed to fetch JavaScript, stylesheets etc. You would need the following value to allow the browser to make requests outside your origin: Remember the segments I talked about? This includes images (img What is Content Security Policy? Nonces are unique one-time-use random values that you generate for each HTTP response, and add to the Content-Security-Policy header, like so: You would then pass this nonce to your view (using nonces requires a non-static HTML) and render script tags that look something like this: Don't create a middleware that replaces all script tags with "script nonce=" because attacker-injected scripts will then get the nonces as well. If you change anything inside the script tag (even whitespace) by, e.g., formatting your code, the hash will be different, and the script won't render. This article brings forth a way to integrate the defense in depth concept to the client-side of web applications. The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between // Intel is committed to respecting human rights and avoiding complicity in human rights abuses. Note: Cisco deprecated support for the Clientless SSL VPN feature in Cisco ASA Software Release 9.17(1). The meta tag must go inside a head tag. To get the hash, look at Google Chrome developer tools for violations like this: Refused to execute inline script because it violates the following Content Security Policy directive: "" Either the 'unsafe-inline' keyword, a hash ('sha256-V2kaaafImTjn8RQTWZmF4IfGfQ7Qsqsw9GWaFjzFNPg='), or a nonce You can also use this hash generator. A Content Protection Policy (CSP) is a security standard that provides an additional layer of protection from cross-site scripting (XSS), clickjacking, and other code injection attacks.It is a defensive measure against any attacks that rely on executing malicious content in a trusted web context, or other attempts to circumvent They are left in there as examples since so many sites include content from those CDNs. Content-Security-Policy: style-src