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[R3] Schneider Electric InduSoft Web Studio and InTouch Machine Edition Remote Code Execution

Critical

Synopsis

While researching CVE-2017-14024 for a Nessus plugin, Tenable found a new stack buffer overflow in InduSoft Web Studio and InTouch Machine Edition. The vulnerability is similar to CVE-2017-14024 in that it involves calling mbstowcs() in TCPServer.dll. However, this new vulnerability leverages command 50 instead of command 49.

The following is a proof of concept:

cat <(echo -ne '\x02\x57\x03\x02\x32'`python -c 'print "A"*0x500'`'\x09\x0a\x03') - | nc <target_host> 1234

A remote unauthenticated attacker can leverage this attack to execute arbitrary code.

Solution

Schneider Electric has released InduSoft Web Studio v8.1 SP1 and InTouch Machine Edition 2017 v8.1 SP1 to address this vulnerability.

Disclosure Timeline

01-18-2018 - Vulnerability discovered
01-28-2018 - Tenable reports the vulnerability to Schneider via webform
01-28-2018 - Schneider acknowledges the vulnerability report and assigns LFSec00000125
03-08-2018 - Schneider asks for Tenable's private key
03-08-2018 - Tenable provides a private key
03-09-2018 - Schneider provides a private build of the fixed version for testing
03-15-2018 - Tenable confirms the private build is patched against this attack

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-2018-8840
Tenable Advisory ID: TRA-2018-07
Credit:
Tenable
CVSSv2 Base / Temporal Score:
10.0 / 7.8
CVSSv2 Vector:
AV:N/AC:L/Au:N/C:C/I:C/A:C
Affected Products:
InduSoft Web Studio v8.1 or prior
InTouch Machine Edition 2017 v8.1 or prior
Risk Factor:
Critical
Additional Keywords:
LFSec00000125
ICSA-18-107-01

Advisory Timeline

04-06-2018 - [R1] Initial Release
04-18-2018 - [R2] Added CVE and ICS-Cert Advisory
05-03-2018 - [R3] Added Link to Additional Information