Siemens SIMATIC S7-1500 CPU

1. EXECUTIVE SUMMARY

• CVSS v3 7.5
• ATTENTION: Exploitable remotely/low skill level to exploit
• Vendor: Siemens
• Equipment: SIMATIC S7-1500 CPU
• Vulnerabilities: Improper Input Validation

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow a denial of service condition of the device.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SIMATIC S7-1500 CPU are affected:

• SIMATIC S7-1500 CPU all versions v1.8.5 and prior, and
• SIMATIC S7-1500 CPU all versions prior to v2.5 down to and including v2.0.

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER INPUT VALIDATION CWE-20

An unauthenticated attacker sending specially crafted network packets to Port 80/tcp or 443/tcp may cause a denial of service on the device.

CVE-2018-16558 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.2    IMPROPER INPUT VALIDATION CWE-20

An unauthenticated attacker sending specially crafted network packets to Port 80/tcp or 443/tcp may cause a denial of service on the device.

CVE-2018-16559 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Energy, Food and Agriculture, Water and Wastewater Systems
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Georgy Zaytsev, Dmitry Sklyarov, Druzhinin Evgeny, Ilya Karpov, and Maxim Goryachy of Positive Technologies reported these vulnerabilities to Siemens.

4. MITIGATIONS

Siemens recommends users upgrade to Version 2.5 or newer. Users who cannot upgrade because of hardware restrictions are recommended to apply the manual mitigations. Updates are available for download from the following link:

https://support.industry.siemens.com/cs/de/en/view/109478459

Siemens also recommends users apply the following manual mitigations:

• Protect network access to Port 80/tcp and Port 443/tcp of affected devices.
• Apply cell protection concept.
• Apply defense-in-depth.

As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security) and following the recommendations in the product manuals.

Additional information on industrial security for Siemens devices can be found at:

https://www.siemens.com/Industrialsecurity

For more information on these vulnerabilities and more detailed mitigation instructions, please see Siemens Security Advisory SSA-180635 at the following location:

http://www.siemens.com/cert/advisories

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.