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Visual Tools DVR multiple vulnerabilities
From: Andrea Fabrizi <andrea.fabrizi () gmail com>
Date: Mon, 15 Oct 2012 23:31:38 +0200

**************************************************************
Title: Visual Tools DVR multiple vulnerabilities
Version affected: VS Series <= 3.0.6.16, VX Series <= 4.2.19.2
Vendor: http://www.visual-tools.com/
Discovered By: Andrea Fabrizi
Email: andrea.fabrizi () gmail com
Web: http://www.andreafabrizi.it
Status: unpatched
**************************************************************

Visual Tools develops, manufactures and commercializes video
surveillance and video observations systems under the global brand
name VideoSafe Technology or under other companies’ brand names.

The DVR systems are based on x86 Debian GNU Linux embedded (aka
emdebian) and the entire framework and software are written using
Python.

After a full reverse engineering of the firmware i discovered some
interesting vulnerabilities, that allow an unauthorized user to access
the DVR web interface and gain a root shell on the system. At the time
i write this advisory, all DVR products commercialized by Visual
Tools, based on this firmware, are vulnerable.

1]======== Administration password disclosure ========
The system expose an hidden cgi that disclose the
Operator/Supervisor/Administrator password if invoked during the first
ten minutes after system boot.

- http://DVR_ADDRESS/cgi-bin/util/passwords.py

Is possible to write a simple script that check the cgi, every five
minutes for example, waiting for the device reboot, that sooner or
later, will happen :)

2]======== Default Administration password ========
As the previous vulnerability, also in this case is possible to access
any DVR system, during the first ten minutes after system boot, using
an hard-coded password.

The default password is: elefante (valid for
Operator/Supervisor/Administrator account)

3]======== Log files disclosure ========
The system expose an hidden cgi that allow any unauthenticated user to
get the system log files. By default the script does not works,
because the zip file is generated into the cgi-bin directory.
But... taking advantage of a directory traversal vulnerability that
affect the same script, is possible to write the zip file into the
apache root directory, and download it directly via browser.

- http://DVR_ADDRESS/cgi-bin/util/ziplogs.py?filename=../../html/logs
- http://DVR_ADDRESS/logs.zip (the zip file generated)

Moreover, the file "service.log" contains the Session ID of the
authenticated user, that can be used to hijack an existing session.

4]======== recv_ip_filtering.py command injection ========
Is possible, for authenticated users, to exploit a command injection
vulnerability that affects the script
/cgi-bin/conf/recv_ip_filtering.py.
This script, used to add or remove ip addresses from the local
iptables, accept one parameter that contains a list of IPs separated
by space, so is not possible to execute directly a command that
contains a space char. A workaround can be done passing the command
through an http header (user-agent for example), and invoking the
corresponding environment variable.

This is a sample request:
#####################################
POST http://DVR_ADDRESS/cgi-bin/conf/recv_ip_filtering.py HTTP/1.1
User-Agent: [COMMAND]
Cookie: language=en; session=VALID_SESSION_ID; user=administrator;
current_page=main/400_Mconf/200_Mnetwork
Content-Type: application/x-www-form-urlencoded
Content-Length: 90

iplistFields=192.168.0.1+192.168.0.2%3b$HTTP_USER_AGENT%3b
#####################################

The command will be executed with the privilege of the apache user.

5]======== init_diskmgr insecure permissions ========
The script "/home/apache/DiskManager/cron/init_diskmgr", writable by
the apache user, is executed by crontab every 15 minutes, with root
privileges. So, editing the script and waiting the scheduled
execution, is possible to run command on the system with root
privileges.

By default the ssh access is denied because the /etc/shadow don't
contains the root password shadow, but exploiting this vulnerability
is possible to add it and gain ssh access to the system.

**************************************************************
TIME-LINE

- 21/09/2012: Vendor contact. No response.
- 15/10/2012: Disclosure.
**************************************************************


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