Server-side include (SSI)

A server-side include (SSI) is an HTML directive that instructs the server to insert the contents of another file into the current document. The included file can be on the same server as the current document, or it can be on a remote server.

Server-side includes are useful for including common pieces of code on multiple pages, such as a header, footer, or navigation menu. They can also be used to dynamically generate content, such as the current date or a list of recent articles.

To use a server-side include, the file must be processed by the server before it is sent to the client. This is usually done by adding a special directive to the server's configuration file. For example, in Apache, the directive would look like this:

AddType text/html .shtml
AddOutputFilter INCLUDES .shtml

This tells the server to treat files with the .shtml extension as HTML files, and to process them for server-side includes.

Once the server is configured, you can use server-side includes in your HTML files by adding the following directive:

Replace "filename" with the path to the file you want to include. For example, to include a file called "header.html" in the same directory as the current file, you would use the following directive:

<!--#include file

What are SSI files?

In order to understand what an SSI file is, it is first necessary to understand what a server-side include (SSI) is. A server-side include is a directive that is placed in a web page by the web developer in order to tell the web server to insert a specific file into the web page before it is sent to the client (browser). The most common use for SSI is to include the contents of a file, such as a menu or header, in multiple pages on a website. This allows the developer to make a change to the included file and have that change reflected on all of the pages that use it, rather than having to make the same change on each individual page.

An SSI file is simply a file that contains server-side includes. These files have a ".ssi" extension and are generally stored in the same directory as the web pages that use them. When a web server receives a request for a page that contains an SSI directive, it will fetch the SSI file and insert its contents into the page before sending the page to the client.

What is server side include injection?

Server side include injection is a type of code injection attack that occurs when user input is not properly sanitized before being used as part of a server-side include directive. This can allow an attacker to inject malicious code into the resulting page that is served to other users.

One way to exploit this vulnerability is to inject a malicious script into the page that will be executed by the browser of any user who views the page. This can be used to steal sensitive information such as cookies or to redirect the user to a malicious website.

Another way to exploit this vulnerability is to inject a malicious file into the server's file system. This can be used to gain access to sensitive information or to perform other actions on the server.

Server side include injection is a serious security vulnerability and should be mitigated by proper input validation and output encoding.

What is server side includes in Apache?

Server side includes (SSI) are directives that are placed in HTML pages, and interpreted by the server while the pages are being served. They are often used to include the contents of a file, or to execute a CGI script. For example, the following directive would include the contents of the file "header.html" at that point in the page:

Server side includes can be used to make a page more dynamic, by including the output of a CGI script, or the current time, or the number of hits the page has received.

SSI directives are not executed by the browser, but by the server. This means that they can only be used on pages that are served by the server, and not on pages that are downloaded from the server (such as HTML pages that are part of a website that is not running on an Apache server).