Absolute Path Traversal

Description

If a product expects a filename as input it is possible that it can construct an absolute path such as "/rootdir/subdir," which is then processed by the operating system to access a file or resource that is outside of a restricted path that was intended by the developer.

This is similar to path traversal but uses only "/" and not ".." to gain access. More detailed information can be found on Path_Traversal

Examples

The following URLs maybe are vulnerable to this attack:

http://testsite.com/get.php?f=list

http://testsite.com/get.cgi?f=2

http://testsite.com/get.asp?f=test

A simple way to execute this attack is like this:

http://testsite.com/get.php?f=/var/www/html/get.php

http://testsite.com/get.cgi?f=/var/www/html/admin/get.inc

http://testsite.com/get.asp?f=/etc/passwd

When the web server returns information about errors in a web application, it is much easier for the attacker to guess the correct locations (e.g. path to the file with a source code, which then may be displayed).