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Quick Summary: When it comes to securing web applications, you might have come across the term “HTTP Security Headers.” These are security measures that can help enhance web app security by adding relevant headers in HTTP requests and responses. But how do they play a role in security? This is what we are going to discuss in this blog. Get a complete understanding by reading till the end.
Web applications are ruling the world nowadays. Most people use one or more web applications each day. While they are useful, they are susceptible to cyberattacks due to various vulnerabilities and misconfigurations. Attackers often target web apps because they are live on the web and have valuable data.
As per Verizon’s DBIR report, they have found that web apps are the main vector for initial entry points of most cyber threats in their ways-in analysis. Hence, the report shows that web app vulnerabilities cause data breaches in most cases.
So, you need robust security measures to protect your web applications from attackers, and one of those measures is HTTP Security Headers. As the name suggests, they are headers used in HTTP requests and responses.
Let’s explore these headers in-depth and find out how they help create secure web applications.
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On This Page
- An Overview of HTTP Security Headers
- Important HTTP Security Headers and Their Role in Security
- Some Outdated Security Headers
- Benefits of Security Headers
- Keep Security Headers in Check with ZeroThreat
A Quick Explanation of HTTP Security Headers
An HTTP header is a field of an HTTP request or response that carries additional information (metadata) and context for that particular request or response. Moreover, the HTTP security headers are those that pertain to security specifically.
So, these headers contain crucial security information. Typically, these headers refer to HTTP response headers in the context of web application security. When a client (web browser) sends a request to the server, the latter generates a response that includes HTTP headers.
In simple words, HTTP security headers dictate how a client browser should behave with a site’s content sent by the server. Besides seamless client-server interactions, it is also a powerful method to prevent web app security risks.
For example, the security header may contain an attribute for a web page that restricts the web browser from opening it inside of a frame. Similarly, another attribute can compel the browser to interact over HTTPS.
So, there are methods where HTTP security headers are helpful in preventing security risks. It can help avoid cyber threats like clickjacking, sensitive data exposure, and cross-site scripting (XSS).
Important HTTP Security Headers and Their Role in Improving Security
There is a wide range of HTTP security headers that provide control over how requests and responses are executed. They either provide restrictions or disable features that could result in potential security issues. The following is the HTTP security headers list explaining important headers that help improve web application security.
Content Security Policy
It is a versatile HTTP header from a security point of view because it covers numerous aspects. CSP (Content Security Policy) is a very powerful and flexible tool to secure web applications. It allows you to control different types of content parameters that prevent malicious content injections or redirections.
CSP is primarily used to define which resources a document can load, especially for JavaScript resources. Besides, it is also used to protect against many cyber threats, especially cross-site scripting. Additionally, it ensures the web pages are loaded over HTTPS to establish secure connections between client and server.
Here is what this header looks like:
Content-Security-Policy: default-src ‘self’
Strict Transport Security
It is the HTTP strict transport security (HSTS) header that ensures secure connections. When this header is applied, the web browser is instructed to always connect to a valid secure connection over HTTPS. If the SSL/TLS certificate is expired or untrusted, the browser refuses the connection with the web app.
It works like:
Strict-Transport-Security: max-age= 31536000; includeSubDomains; preload
The above header will inform the browser that the web application and its subdomains can only be connected via secure HTTPS connections. When a browser uses a URL with “http://”, it will be changed to “https://”. It helps prevent various types of cyberattacks like session hijacking and Man-in-the-Middle attacks.
Cross-Origin Resource Sharing
CORS or Cross-Origin Resource Sharing, is an HTTP-header-based mechanism that enables web browsers to access external resources for a particular web app. Often, web apps require external resources, but accessing such resources is restricted by the Same-Origin Policy of a web browser.
CORS is helpful in accessing external resources without compromising security. It is typically used to fetch JavaScript resources that are stored on other domains. A server defines any other origin, like domain, port, or scheme, other than its own, from where the browser should allow the loading of resources.
Fetching external resources with CORS ensures a secure mechanism to load resources from other origins. The browser makes a preflight request to the server hosting CORS to check if it will permit the actual request.
Access-Control-Allow-Origin is the CORS header you can use to define a specific origin to fetch resources or use “ * ” for all origins.
It works like:
Access-Control-Allow-Origin: https://examplesite.com
There are other headers related to it:
- Cross-Origin-Opener-Policy (COOP): This header controls the behavior of a new top-level document that could be opened by navigating to a new page or using Window.open(). It defines whether the document shares the browsing context with the cross-origin resource or opens a new one.
- Cross-Origin-Embedder-Policy (COEP): The COEP header controls the configuration related to embedding cross-origin resources into the document.
- Cross-Origin-Resource-Policy (CORP): This header provides protection against requests from other origins, specifically those that include
"<img>"
,"<script>"
, and similar elements.
X-Content-Type-Options
When a server generates a response with the X-Content-Type-Options header, it forces the browser to strictly adhere to the MIME type specified in the Content-Type header. Even the browser shouldn’t try detection of the content type in case there is no Content-Type header defined.
It protects from MIME type sniffing attacks and cross-site scripting by restricting the browser to use content type unless specified. There is only one directive for it and it works like this:
X-Content-Type-Options: nosniff
Cache-Control
This HTTP security header is used to manage caching in different areas like browsers and shared caches (CDNs, Proxies, etc). It has different kinds of directives that are used in both HTTP requests and responses.
By using this header, it is possible to prevent caching of server responses. As a result, it helps avoid storing any confidential data in the caches. Directives can be leveraged to modify the behavior, such as adjusting the expiration time of the cache.
Example use of this header is:
Cache-Control: no-store
Referrer-Policy
This HTTP header provides control over the amount of referred information, if any, a browser can share with the server. If this setting is enabled for browsers with the “origin-when-cross-origin" directive, the full referrer information will be shared if the requests are of the same origin. In the case of other requests, the information will be limited to the origin only.
It is typically used as follows:
Referrer-Policy: origin-when-cross-origin
Permissions-Policy
This header was previously known as “Feature-Policy” which defines permissions for certain browser-based features and APIs on the existing web page. This header is useful in controlling permissions for application-specific features.
However, this header is primarily used to prevent access to privacy-related features that include geolocation, microphone, and camera. So, using this header, it is possible to control the access to specific features that could affect a user’s privacy.
It can be used like:
Permissions-Policy: picture-in-picture=(), geolocation=()
This will restrict access to Picture-in-Picture and Geolocation features. There are different directives to control the access that you can find in MDN’s documentation.
Clear-Site-Data
It is an HTTP response header that instructs a browser to remove all kinds of browsing data (only specific types like cache, cookie, and storage) for the site it is requesting. Consequently, it offers control over what kind of data browsers can store for a specific origin.
This is a very useful method to protect confidential information by ensuring that the browser doesn’t store such data when logged out from a web app.
This header can be set as:
Clear-Site-Data: “*”
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Some Outdated HTTP Security Headers
There are many HTTP security headers that have been deprecated. Many of these headers were introduced as temporary fixes for security issues arising in the past. However, as the web has become more structured and standardized, these old headers have been deprecated. Although they aren’t recommended for modern web development, taking an insight into them is worth it for older web applications.
X-XSS-Protection
This was a response header supported by old Safari, Chrome, and Internet Explorer browsers. With this feature, browsers could stop the loading of web pages if they detected reflected XSS attacks. This header was useful to prevent JavaScript attacks back in time, but it’s not effective now because modern browsers don’t use XSS filters.
The syntax was:
X-XSS-Protection: 1, mode=block
X-Frame-Options
Frames were widely used in web pages in the past which opened new security issues. So, X-Frame-Options was provided as a way to mitigate the security risks. XSS attacks used iframes to cause malicious redirections.
It works like:
X-Frame-Options: deny
After this, it will prevent web pages from being loaded into iframes. Besides, the web pages in the same origin can be allowed to load into iframes with the use of x-frame-options: sameorigin header.
Public-Key-Pins
HPKP (HTTP Public Key Pinning) was a feature of Firefox and Google Chrome to prevent certificate spoofing. Well, it was a complicated method because the server would provide the client with the cryptographic hashes of the public key of valid certificates. It will be used for future communication. There were many problems with it and if it is not configured properly, it could prevent access to a site for the time period specified in the header.
It was used this way:
Public-Key-Pins: pin-sha256=”cUPcBAZRKaASuZWhtneDhtWqY3oBSkE3h5+soZS9sWp=”; max-age=7776000
How Do HTTP Security Headers Help?
Today, cyberattacks are widespread. Attackers take advantage of misconfigurations or security weaknesses in web apps to carry out attacks. HTTP security headers can help strengthen web app security by avoiding unexpected behavior. As a result, it prevents malicious intents of attackers and keeps your data safe. There are many ways these headers ensure security, as mentioned below.
Prevent Unsecure Connections
Attackers can use tactics like SSL hijacking to force users to connect to an insecure server over HTTP connections. But thanks to security headers like strict transport security that prevents such connections and converts them to HTTPS connections.
Avoid Cross-Site Scripting Attacks
XSS attack allows an attacker to overcome the same-origin policy of a web browser to perform actions on a user’s behalf. It enables the attacker to access a user’s data. The attacker injects scripts on the web page in a vulnerable web app, which is executed in the user’s browser. There are various HTTP security headers like “X-Frame-Options", CORS, and CSP that prevent XSS attacks.
Limit Dangerous Functionality
Another advantage of the security headers is that they are useful in limiting some dangerous functionality that is designed in web protocols. For example, it can prevent attackers from embedding malicious code in websites by limiting the ability to implement content from external sources.
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Keep Security Headers in Check with ZeroThreat
HTTP security headers are an effective and simple method to improve web application security. So, enabling these headers is a good idea. However, due to misconfigurations or lack of awareness, organizations miss many of these headers, which leads to security loopholes.
There comes the role of an AI-powered vulnerability scanner – ZeroThreat. It can dynamically scan applications and discover the missing HTTP security headers vulnerability that could pose a threat. It checks applications for recommended headers and reports issues precisely with 98.9% accuracy.
ZeroThreat is a powerful DAST tool that can discover more than common vulnerabilities and misconfigurations. It can detect zero-day/n-day/1-day exploits, out-of-band vulnerabilities, and thousands of other CVEs. Get an overview of this tool to know more.
Frequently Asked Questions
Can HTTP security headers enhance web app resilience?
Yes, they play an important role in securing web applications by mitigating risks like XSS, clickjacking, CSRF, etc. They help build secure and resilient applications that prevent cyber risks.
How to implement security headers to improve web app security posture?
How do security headers enhance web app protection?
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