OWASP Mutillidae II: Web Pwn in Mass Production
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Arbitrary File Inclusion
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Current Page: arbitrary-file-inclusion.php |
Notice that the page displayed by Mutillidae is decided
by the value in the "page" URL parameter. What could possibly go wrong?
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PHP runs on an account (like any other user). The account has privileges
to the local file system with the ability to read, write, and/or execute files.
Ideally the account would only have enough privileges to execute php files
in a certain, intended directory but sadly this is often not the case.
Local File Inclusion occurs when a file to which the PHP account has
access is passed as a parameter to the PHP function "include", "include_once",
"require", or "require_once". PHP incorporates the content into the page. If
the content happens to be PHP source code, PHP executes the file.
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Remote File Inclusion occurs when the URI of a file located on a different
server is passed to as a parameter to the PHP function "include", "include_once",
"require", or "require_once". PHP incorporates the content into the page. If
the content happens to be PHP source code, PHP executes the file.
Note that on newer PHP servers the configuration parameters "allow_url_fopen"
and "allow_url_include" must be set to "On".
By default, these may or may not
be "On" in newer versions. For example, by default in XAMPP 1.8.1,
"allow_url_fopen = On" by default but "allow_url_include = Off" by default. If you
wish to try remote file inclusion, be sure these configuration parameters are set
to "On" by going to the php.ini file, locating the parameters, setting their value to
"On", and restarting the Apache service. An example of this configuration appears below.
;;;;;;;;;;;;;;;;;;
; Fopen wrappers ;
;;;;;;;;;;;;;;;;;;
; Whether to allow the treatment of URLs (like http:// or ftp://) as files.
; http://php.net/allow-url-fopen
allow_url_fopen = On
; Whether to allow include/require to open URLs (like http:// or ftp://) as files.
; http://php.net/allow-url-include
allow_url_include = On
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