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[R1] NUUO NVRMini2 Authenticated Command Injection

Critical

Synopsis

While developing a Nessus plugin, Tenable found that CVE-2018-14933 was insufficiently patched. NUUO originally tried to fix CVE-2018-14933 by enforcing authentication on upgrade_handle.php. They also introduced the following logic in an attempt to filter out uploaddir variables with system commands:

$uploaddir = $_GET['uploaddir'];
if(strpos($uploaddir, ';') !== false)
{
    die('[1]Not a valid path.');
}

However, the above logic doesn't account for other techniques, such as using logical operators, to inject shell commands. If a remote authenticated attacker set uploaddir to "|| whoami" then it would bypass the filter and the "whoami" command would be executed as part of the following logic:

$current_dir = system('cat '.PHP_CINF_PATH.'| grep \'upload_tmp_dir\'');
$tmp_upload_dir = 'upload_tmp_dir='.$uploaddir;
$cmd = "sed -i 's/".str_replace('/', '\/', $current_dir)."/".str_replace('/', '\/', $tmp_upload_dir)."/g' ".PHP_CINF_PATH;
                    
system($cmd);

A full proof of concept can be found in our GitHub repository.

Solution

Upgrade to firmware version 3.10.0 or later.

Disclosure Timeline

09/18/2018 - A write up and PoC sent to NUUO. 90 day date set to Dec. 19.
10/12/2018 - Tenable asks NUUO to confirm receipt.
10/17/2018 - NUUO provides new contact.
10/22/2018 - Tenable asks the new contact if NUUO is aware of the issue and working on it.
10/22/2018 - NUUO says it will be patched in 3.10.0 in the late Nov. release.
11/29/2018 - NUUO releases a fix in 3.10.0.

All information within TRA advisories is provided “as is”, without warranty of any kind, including the implied warranties of merchantability and fitness for a particular purpose, and with no guarantee of completeness, accuracy, or timeliness. Individuals and organizations are responsible for assessing the impact of any actual or potential security vulnerability.

Tenable takes product security very seriously. If you believe you have found a vulnerability in one of our products, we ask that you please work with us to quickly resolve it in order to protect customers. Tenable believes in responding quickly to such reports, maintaining communication with researchers, and providing a solution in short order.

For more details on submitting vulnerability information, please see our Vulnerability Reporting Guidelines page.

If you have questions or corrections about this advisory, please email [email protected]

Risk Information

CVE ID: CVE-2018-15716
Tenable Advisory ID: TRA-2018-41
Credit:
Artem Metla
CVSSv2 Base / Temporal Score:
9.0 / 7.4
CVSSv2 Vector:
AV:N/AC:L/Au:S/C:C/I:C/A:C
Nessus Plugin ID: 119326
Affected Products:
NUUO NVRMini2 3.9.1
Risk Factor:
Critical

Advisory Timeline

11/29/2018 - [R1] Initial Release