Upload

Uploaded files may pose a significant risk if not handled correctly. A remote attacker could send a multipart/form-data POST request with a specially-crafted filename or mime type and execute arbitrary code.

Tools

• Fuxploider

Exploits

PHP Extension

.php
.php3
.php4
.php5
.php7

Less known extensions
.pht
.phar
.phpt
.pgif
.phtml
.phtm

Double extensions
.jpeg.php
.jpg.php
.png.php

Upload tricks

• Null byte (eg: shell.php%00.gif, shell.php%00.png), works well against pathinfo()
• Mime type, change Content-Type : application/x-php or Content-Type : application/octet-stream to Content-Type : image/gif

Picture upload with LFI

Valid pictures hosting PHP code. Upload the picture and use a local file inclusion to execute the code. The shell can be called with the following command : curl 'http://localhost/test.php?0=system' --data "1='ls'".

• Picture Metadata, hide the payload inside a comment tag in the metadata.
• Picture Resize, hide the payload within the compression algorithm in order to bypass a resize. Also defeating getimagesize() and imagecreatefromgif().

Configuration Files

• .htaccess
• web.config
• httpd.conf
• __init__.py

CVE - Image Tragik

HTTP Request
Reverse Shell
Touch command

References

• Bulletproof Jpegs Generator - Damien "virtualabs" Cauquil
• BookFresh Tricky File Upload Bypass to RCE, NOV 29, 2014 - AHMED ABOUL-ELA
• Encoding Web Shells in PNG IDAT chunks, 04-06-2012, phil
• La PNG qui se prenait pour du PHP, 23 février 2014