Testing for Local File Inclusion LFI

How to Test

Since LFI occurs when paths passed to "include" statements are not properly sanitized, in a blackbox testing approach, we should look for scripts which take filenames as parameters.

Consider the following example:

http://vulnerable_host/preview.php?file=example.html

This looks as a perfect place to try for LFI. If an attacker is lucky enough, and instead of selecting the appropriate page from the array by its name, the script directly includes the input parameter, it is possible to include arbitrary files on the server.

Typical proof-of-concept would be to load passwd file:

http://vulnerable_host/preview.php?file=../../../../etc/passwd

If the above mentioned conditions are met, an attacker would see something like the following:

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
alex:x:500:500:alex:/home/alex:/bin/bash
margo:x:501:501::/home/margo:/bin/bash
...

Very often, even when such vulnerability exists, its exploitation is a bit more complex. Consider the following piece of code:

<?php “include/”.include($_GET['filename'].“.php”); ?>

In the case, simple substitution with arbitrary filename would not work as the postfix 'php' is appended. In order to bypass it, a technique with null-byte terminators is used. Since effectively presents the end of the string, any characters after this special byte will be ignored. Thus, the following request will also return an attacker list of basic users attributes:

http://vulnerable_host/preview.php?file=../../../../etc/passwd
http://vulnerable_host/preview.php?file=../../../../etc/passwdjpg

source : https://www.owasp.org/index.php/Testing_for_Local_File_Inclusion

Comments

VM 9 : PHP Include And Post Exploitation

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VM 5: Vulnix :

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Penetration Testing Framework 0.57

Network Footprinting (Reconnaissance) The tester would attempt to gather as much information as possible about the selected network. Reconnaissance can take two forms i.e. active and passive. A passive attack is always the best starting point as this would normally defeat intrusion detection systems and other forms of protection etc. afforded to the network. This would usually involve trying to discover publicly available information by utilising a web browser and visiting newsgroups etc. An active form would be more intrusive and may show up in audit logs and may take the form of an attempted DNS zone transfer or a social engineering type of attack. http://www.vulnerabilityassessment.co.uk/

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