Code injection (php://input wrapper)
Critical Web Application Scanning Plugin ID 98121
Synopsis
Code injection (php://input wrapper)
Description
A modern web application will be reliant on several different programming languages.
These languages can be broken up in two flavours. These are client-side languages
(such as those that run in the browser -- like JavaScript) and server-side
languages (which are executed by the server -- like ASP, PHP, JSP, etc.) to form
the dynamic pages (client-side code) that are then sent to the client.
Because all server-side code should be executed by the server, it should only ever
come from a trusted source.
Code injection occurs when the server takes untrusted code (ie. from the client)
and executes it.
Cyber-criminals will abuse this weakness to execute arbitrary code on the server,
which could result in complete server compromise.
Scanner was able to inject specific server-side code via a PHP wrapper (`php://input`)
and have the executed output from the code contained within the server response.
This indicates that proper input sanitisation is not occurring.
Solution
It is recommended that untrusted input is never processed as server-side code.
To validate input, the application should ensure that the supplied value contains only the data that are required to perform the relevant action.
For example, where a username is required, then no non-alpha characters should not be accepted.