ESB-2019.0343 - [Appliance] Kunbus PR100088 Modbus Gateway: Multiple vulnerabilities 2019-02-06

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0343
          Multiple vulnerabilities have been identified in Kunbus
                          PR100088 Modbus Gateway
                              6 February 2019

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Kunbus PR100088 Modbus Gateway
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Existing Account      
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-6533 CVE-2019-6529 CVE-2019-6527

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-19-036-05

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Advisory (ICSA-19-036-05)

Kunbus PR100088 Modbus Gateway

Original release date: February 05, 2019

Legal Notice

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referenced in this product or otherwise. Further dissemination of this product
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1. EXECUTIVE SUMMARY

CVSS v3 10.0

ATTENTION: Exploitable remotely/low skill level to exploit

Vendor: Kunbus

Equipment: PR100088 Modbus gateway

Vulnerabilities: Improper Authentication, Missing Authentication for Critical
Function, Improper Input Validation

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to 
achieve remote code execution and/or cause a denial-of-service condition.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of PR100088 Modbus gateway are affected:

PR100088 Modbus gateway: All versions prior to Release R02 (or Software 
Version 1.1.13166)

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER AUTHENTICATION CWE-287

An attacker may be able change the password for an admin user who is currently
or previously logged in, provided the device has not been restarted.

CVE-2019-6527 has been assigned to this vulnerability. A CVSS v3 base score of
9.6 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H).

3.2.2 MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306

Registers used to store Modbus values can be read and written from the web 
interface without authentication.

CVE-2019-6533 has been assigned to this vulnerability. A CVSS v3 base score of
10.0 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)

3.2.3 IMPROPER INPUT VALIDATION CWE-20

An attacker could specially craft an FTP request that could crash the device.

CVE-2019-6529 has been assigned to this vulnerability. A CVSS v3 base score of
4.9 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Communication

COUNTRIES/AREAS DEPLOYED: Worldwide

COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Nicolas Merle of Applied Risk reported these vulnerabilities to NCCIC. NCCIC 
coordinated these vulnerabilities with BSI Germany.

4. MITIGATIONS

Kunbus recommends the following:

Update to Version R02; the updated file can be downloaded from the link below
(installation instructions can be found in the readme file included in the 
download): 
https://www.kunbus.com/productsecurity/security-topic-1.html?file=files/media/bugfixes/SU_100088_R02.zip

These devices are not intended to be used in a public network. Rather, these 
devices are intended for use in an industrial environment with a protected 
network architecture.

NCCIC recommends users take defensive measures to minimize the risk of 
exploitation of this vulnerability. Specifically, users should:

Minimize network exposure for all control system devices and/or systems, and 
ensure that they are not accessible from the Internet.

Locate control system networks and remote devices behind firewalls, and 
isolate them from the business network.

When remote access is required, use secure methods, such as Virtual Private 
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize that VPN is only
as secure as the connected devices.

NCCIC reminds organizations to perform proper impact analysis and risk 
assessment prior to deploying defensive measures.

NCCIC also provides a section for control systems security recommended 
practices on the ICS-CERT web page. Several recommended practices are 
available for reading and download, including Improving Industrial Control 
Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly 
available on the ICS-CERT website in the Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies.

Organizations observing any suspected malicious activity should follow their 
established internal procedures and report their findings to NCCIC for 
tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.

Contact Information

For any questions related to this report, please contact the NCCIC at:

Email: NCCICCUSTOMERSERVICE@hq.dhs.gov

Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information: 
http://ics-cert.us-cert.gov

or incident reporting: https://ics-cert.us-cert.gov/Report-Incident?

The NCCIC continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 
product.

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