Siemens SIMATIC S7-1500 CPU Vulnerabilities

OVERVIEW

Siemens has identified two vulnerabilities in the Siemens SIMATIC S7-1500 CPU family. Siemens has produced a firmware update to mitigate these vulnerabilities.

These vulnerabilities could be exploited remotely.

AFFECTED PRODUCTS

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

• Siemens SIMATIC S7-1500 CPU family, versions prior to Version 1.8.3

IMPACT

Successful exploitation of these vulnerabilities could result in a denial-of-service condition or a replay attack on the affected devices.

Impact to individual organizations depends on many factors that are unique to each organization. NCCIC/ICS-CERT recommends that organizations evaluate the impact of these vulnerabilities based on their operational environment, architecture, and product implementation.

BACKGROUND

Siemens is a multinational company headquartered in Munich, Germany.

The affected products, the Siemens SIMATIC S7-1500 CPU family, are designed for discrete and continuous control in industrial environments. According to Siemens, the Siemens SIMATIC S7-1500 CPU family is deployed across several sectors including Critical Manufacturing, Food and Agriculture, and Chemical. Siemens estimates that these products are used worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

INSUFFICIENT CONTROL FLOW MANAGEMENTCWE-691: Insufficient Control Flow Management, http://cwe.mitre.org/data/definitions/691.html, web site last accessed February 9, 2016.

Specially crafted packets sent to Port 102/TCP (ISO/TSAP) could cause a denial-of-service condition on affected devices. The CPU will automatically restart and remain in STOP mode. To recover from this condition, the CPU needs to be manually put into RUN mode again.

CVE-2016-2200NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-2200, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, web site last accessed February 9, 2016.

PREDICTABILITY PROBLEMSCWE-340: Predictability Problems, http://cwe.mitre.org/data/definitions/340.html, web site last accessed February 9, 2016.

The replay protection efficiency at Port 102/TCP (ISO/TSAP) of the affected devices could be reduced by remote attackers under certain conditions.

CVE-2016-2201NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-2201, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v3 base score of 3.7 has been assigned; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N, web site last accessed February 9, 2016.

VULNERABILITY DETAILS

EXPLOITABILITY

These vulnerabilities could be exploited remotely.

EXISTENCE OF EXPLOIT

No known public exploits specifically target these vulnerabilities.

DIFFICULTY

An attacker with low skill would be able to exploit one of these vulnerabilities.

MITIGATION

Siemens has released SIMATIC S7-1500 firmware Version 1.8.3, which addresses the identified vulnerabilities and recommends that users update to the new firmware version, which is available at the following URL:

<https://support.industry.siemens.com/cs/de/en/view/109478459&gt;.

As a general security measure, Siemens strongly recommends that users protect network access to SIMATIC S7-1500 CPUs. Siemens advises users to configure the host environment according to operational guidelines, provided in the following URL:

<https://www.siemens.com/cert/operational-guidelines-industrial-security&gt;.

Siemens security advisory, SSA-253230, is available at the following URL:

<https://www.siemens.com/cert/advisories&gt;.

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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.

ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

ICS-CERT also provides a section for control systems security recommended practices on the ICS-CERT web page at: http://ics-cert.us-cert.gov/content/recommended-practices. 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 in the ICS‑CERT Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies, that is available for download from the ICS-CERT web site (http://ics-cert.us-cert.gov/).

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