The security risks of HTML5 applications need to be paid attention to in front-end development, mainly including XSS attacks, interface security and third-party library risks. 1. Prevent XSS: Escape user input, use textContent, CSP header, input verification, avoid eval() and direct execution of JSON; 2. Protect interface: Use CSRF Token, SameSite Cookie policies, request frequency limits, and sensitive information to encrypt transmission; 3. Securely use third-party libraries: periodic audit dependencies, use stable versions, reduce external resources, enable SRI verification, ensure that security lines have been built from the beginning of development.

Security issues are often easily overlooked during front-end development, especially when building HTML5 web applications. Many people think that as long as the code is written correctly, the function will be free, but in fact, many common vulnerabilities are hidden in the details. If your application does not deal with these security risks, the least data will be leaked, and the worst system will be compromised.

The following lists several of the most common and most overlooked security issues, as well as corresponding protection suggestions.

Prevent cross-site scripting attacks (XSS)

XSS is one of the most classic security vulnerabilities in web applications. Attackers inject malicious scripts into pages that execute when other users access the page, which may steal cookies, hijack sessions, or even initiate fake requests.

How to prevent it?

• All user input must be escaped, such as using textContent instead of innerHTML to insert content.
• Use CSP (Content Security Policy) header to limit which source scripts can be executed.
• Input verification is done on both the server and the front end, filtering or encoding special characters.
• Don't use eval() easily or execute JSON strings directly as JSS.

For example: If the user comment box allows submission of content like <script>alert(&#39;xss&#39;)</script> and is displayed directly on the page without escape, the script will be executed.

Protect your forms and API interfaces

Many developers only focus on whether the front-end functions are normal, but ignore the security of the back-end interface. Especially under the front-end separation architecture, the front-end calls the back-end API through AJAX. If there is no proper protection, it is easy to become the target of attack.

Some practical suggestions:

• Use CSRF Token to prevent cross-site request forgery attacks, especially in key operations such as login and payment.
• Enable the SameSite Cookie Policy for all POST requests to avoid cookies being carried by third-party websites.
• Set reasonable request frequency limits to prevent brute force or DDoS attacks.
• Sensitive information should not be transmitted plain text, such as passwords should be encrypted with hash, and important fields should be considered to use HTTPS encryption channels.

For example, a login interface without a frequency limit may be blocked by an attacker trying a combination of username and password, resulting in account leaks.

Securely use third-party libraries and plug-ins

Modern web applications are inseparable from various third-party JavaScript libraries and components, but this also brings potential security risks. Some older versions of the library have known vulnerabilities, and the consequences will be serious once exploited.

What should be done?

• Check project dependencies regularly and use tools like npm audit to find risks.
• Try to use the official stable version and do not introduce unknown JS files at will.
• Reduce unnecessary dependencies, the less external resources mean the smaller the attack surface.
• Use Subresource Integrity (SRI) technology to ensure that the loaded remote scripts are not tampered with.

For example, if you use jQuery 2.x version, and it has a DOM XSS vulnerability, even if you do not write the wrong code yourself, it may be exploited by the attacker.

Basically, these common problems and solutions. Safety is not something that can be achieved overnight, but as long as you pay conscious attention to these points from the beginning of development, you can greatly reduce risks. Don't wait until something happens before thinking about remedy it.

The above is the detailed content of Securing HTML5 web applications against common vulnerabilities. For more information, please follow other related articles on the PHP Chinese website!