Website Content Security Policy

How to Get Started with Your Website Content Security Policy?

Website security (Content Security Policy) is increasingly becoming a concern for both web developers and users. More so, the new wave of web apps has become even more relevant to beef up their security. Regardless of its primary function, ensuring that your web app has the essential security features is only rewarding. One of these features is Content Security Policies.

Web Content Security Policies (CSPs)

Web applications are usually susceptible to cross-site scripting attacks and XSS, among other black hat injection threats. Their threat is typically vast and dangerous. Nonetheless, it’s the directive of CSPs to mitigate and ease them. CSPs refer to standard policies or rules set by web developers on the web app framework to stipulate what content to load and render to the web user. This measure ensures that malicious data harvesting does not happen to them at any moment. 

It may be hard to know if your web app has the necessary measures to secure the app for you and your users, even after evaluating it with the Mozilla Observatory tool. It’s also worth noting that not all web browsers respond to CSPs. Therefore, you should contact experts who will give you a detailed report of your site’s vulnerability. One thing to note, however, is that threats such as XSS are complex to block. Then again, with various CSPs, you will be a step forward if you do not lead with web security. 

Common Web Vulnerabilities 

1. Cross-site Scripting, XSS

This is a situation whereby cybercriminals expose your site to the threat of external content injections with external scripts on the client side. These criminals bypass laws by gaining access controls to web pages, controlling data, and modifying logs.

2.SQL Injections 

Web apps with login dialogues on different pages or pop-ups are highly vulnerable to SQL injections. This injection happens when an attacker tricks a client into submitting delicate information, such as credit card details, by pushing scripts that override the existing information. 

This vulnerability can be erased by whitelisting login fields with trusted service providers and limiting what the client or user sees in case of a login error. This information could be helpful to an attacker. 

3. Insecure Cryptographic Storage 

Data security is a big concern. As a web app user or even developer, you need to ensure WHAT, WHERE, and HOW are questions you can answer about data storage. It’s imperative to ensure that data is stored securely with hashes that are not easily cracked. 

4. Failure To Restrict URL Access 

An attacker may modify a URL, leading to sensitive content for their gain, and expose the client to a data breach. For instance, hackers will change the suffix of a URL to receive the data the user submits instead of it going to the server admin.  

5. Unvalidated Redirects 

This issue has happened to many web users. Here, both external and internal links to resources create this vulnerability. An attacker will modify a URL that redirects the client with a slight addition that will lead them to external and malicious sites. To avoid this, reducing redirects on the web app is advised.

As we have seen, it’s pretty easy for your web app to be vulnerable to cyberbullying attacks if CSPs are not in place. CSPs are like traffic police; they mitigate and report vulnerabilities and risks before they happen. 

Thus, here are the steps you can take to implement a comprehensive CSP on your web applications. 

1. Prepare A List of All The Resources That Your Web App Uses

We have already talked about the common resources that your site has, such as text and images. For this part, you must map out all of them, such as iframes, audio, video, scripts, stylesheets, and workers. 

To find the resources on your web app, you can use the developer tool on your browser to inspect the resources or determine them directly from your site’s analytics provider. 

2. Write a Policy

This step can also be called rule-setting. From the resources you have determined, it’s now upon you or your developer to come up with directives. To start with, default CSPs are set. These defaults act as umbrella policies for any resource. 

For example, the directive script-src is a default CSP specifying valid JavaScript sources. This rule falls under default-src in that if it’s not stated, the browser will look for default-src, and still submit to it.

3. Creating a Reporting Directive 

When you are confident that your website or web app features are secured, you need a directive policy that reports an attempt to violate it. A common example is the report-uri. This policy will report direct attacks and not vulnerabilities experienced on your web app. 

Most browsers support this directive. However, an improved reporting directive, report-to, is being championed in browsers that support it. 

4. Fixing Violations 

Some violations are legitimate, while others are not, which means that a reporting directive might report a particular vulnerability, which, to the user, it was not. To account for that, the framework for the web app will need to be revised to adjust the errors. For instance, some web app development frameworks might restrict the users’ control over the CSP. If that happens, you may lose clients relying on your web app. 

5 .Deploy CSPs in Strict Mode

After you have fixed and adjusted the directives in test mode, analyzed the possible violations, and fixed them, it’s time to enforce them in report-only mode. This means any vulnerabilities will be reported directly. 

Deployment is done primarily in two ways: using HTTP headers and meta tags. Depending on the design or preferences, you can choose any of these that fit in with your web app. Nevertheless, whichever method you opt for will serve a similar purpose as the other one. The good news is that you can use both if you are unsure what to do. More so, the HTTP header is deemed most effective compared to meta elements. HTTP headers are more effective than meta tags because they are executed before content modification happens.

Strategies To Enforce CSPs 

a. Whitelisting Domains 

Whitelisting is the act of allowing access to entities or privileges to resources. Domain extensions and query strings can be directed on how they interact with your site’s content. By so doing, attackers will be blocked and reported for illegal content modification.

b.Employing Cryptographic Nonces 

A nonce is a random number that’s only used once after it has been cryptographically created to hide trails. Nonces are required for every refresh or page load that the user executes. With a nonce, an attacker cannot successfully affect a user with an injection since full access will be unavailable for them without the nonce used. 

c.Hashing

Hashes are also untraceable alternatives to nonces. A hash function is used to provide fixed-size values from keys. In this case, a developer can create a hash that executes a CSP rule. Without the hash value, the CSP will mitigate the vulnerability and report it as a violation. Hence, hashing is undoubtedly a strategy worth incorporating into your CSP implementation.

Conclusion 

A fine line exists between vulnerability and risk when web security is in context. Even so, vulnerabilities are the root of risks. Risk is defined as the product of threat and vulnerability. But what does that mean? Web apps are created by relying on open-source code libraries. This fact means they are susceptible to modification even after others have built on them. However, we are not implying that your web app is unsafe if created by open-source libraries. In short, employing CSPs for large web apps can be difficult. However, with a checklist and a laid-out plan like the one above, you will be steps ahead regarding content security for you and your clients.