Visual Tools DVR multiple vulnerabilities

Type securityvulns
Reporter Securityvulns
Modified 2012-10-17T00:00:00


Title: Visual Tools DVR multiple vulnerabilities Version affected: VS Series <=, VX Series <= Vendor: Discovered By: Andrea Fabrizi Email: Web: 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/

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/
  • http://DVR_ADDRESS/ (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]======== command injection ======== Is possible, for authenticated users, to exploit a command injection vulnerability that affects the script /cgi-bin/conf/ 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/ 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


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.


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