Rockwell Automation Micrologix 1100 and 1400 PLC Systems Vulnerabilities (Update A)

OVERVIEW

This updated advisory is a follow-up to the original advisory titled ICSA-15-300-03 Rockwell Automation MicroLogix 1100 and 1400 PLC Systems Vulnerabilities that was published October 27, 2015, on the NCCIC/ICS-CERT web site.

Ilya Karpov of Positive Technologies, David Atch of CyberX, and independent researcher Aditya Sood independently identified vulnerabilities in Rockwell Automation’s Allen-Bradley MicroLogix 1100 and 1400 programmable logic controller (PLC) systems.

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Rockwell Automation has produced new firmware versions to mitigate the vulnerabilities to include a previously unresolved buffer overflow vulnerability in the Allen-Bradley MicroLogix 1400.

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These vulnerabilities could be exploited remotely.

AFFECTED PRODUCTS

The following Allen-Bradley MicroLogix 1100 controller platforms are affected:

• 1763-L16AWA, Series B, Version 14.000 and prior versions,
• 1763-L16BBB, Series B, Version 14.000 and prior versions,
• 1763-L16BWA, Series B, Version 14.000 and prior versions,
• 1763-L16DWD, Series B, Version 14.000 and prior versions,
• 1763-L16AWA, Series A, Version 14.000 and prior versions,
• 1763-L16BBB, Series A, Version 14.000 and prior versions,
• 1763-L16BWA, Series A, Version 14.000 and prior versions, and
• 1763-L16DWD, Series A, Version 14.000 and prior versions.

The following Allen-Bradley MicroLogix 1400 controller platforms are affected:

• 1766-L32AWA, Series B, Version 15.002 and prior versions,
• 1766-L32AWAA, Series B, Version 15.002 and prior versions,
• 1766-L32BWA, Series B, Version 15.002 and prior versions,
• 1766-L32BWAA, Series B, Version 15.002 and prior versions,
• 1766-L32BXB, Series B, Version 15.002 and prior versions,
• 1766-L32BXBA, Series B, Version 15.002 and prior versions,
• 1766-L32AWA, Series A, Version 15.002 and prior versions,
• 1766-L32AWAA, Series A, Version 15.002 and prior versions,
• 1766-LK32BWA, Series A, Version 15.002 and prior versions,
• 1766-L32BWAA, Series A, Version 15.002 and prior versions,
• 1766-L32BXB, Series A, Version 15.002 and prior versions, and
• 1766-L32BXBA, Series A, Version 15.002 and prior versions.

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The buffer overflow vulnerability also affects the aforementioned Allen-Bradley MicroLogix 1400 controller platforms, firmware Version 15.003 and prior versions.

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IMPACT

Successful exploitation of the vulnerabilities may allow a remote attacker to escalate privileges, execute arbitrary code, and cause a denial-of-service condition.

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

BACKGROUND

Rockwell Automation, which is a US-based company, provides industrial automation control and information products worldwide across a wide range of industries.

The affected products, Allen-Bradley MicroLogix 1100 and 1400, are PLCs. According to Rockwell Automation, these products are deployed across several sectors, including Chemical, Critical Manufacturing, Food and Agriculture, Water and Wastewater Systems, and others. Rockwell Automation estimates that these products are used worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

A buffer overflow vulnerability exists in a vulnerable function that may crash the device or allow arbitrary code execution.

CVE-2015-6490NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6490, web site last accessed December 08, 2015. has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H/I:H/A:H, web site last accessed October 27, 2015.

A specifically crafted web request may allow a remote attacker to crash the device, which would require the device to be power cycled to restore it to a working state.

CVE-2015-6492NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6492, web site last accessed December 08, 2015. 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 October 27, 2015.

A remote attacker could redirect external web content into the device’s web page frame, allowing remote file inclusion. This vulnerability was identified in ICS-ALERT-15-225-02A Rockwell Automation 1766-L32 Series Vulnerability, released on August 20, 2015.

CVE-2015-6491NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6491, web site last accessed December 08, 2015. has been assigned to this vulnerability. A CVSS v3 base score of 4.6 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N). CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N, web site last accessed October 27, 2015.

This vulnerability may allow an attacker to inject and store Javascript in the device’s web server, which would be executed on the user’s web browser when accessing the embedded web server function. The stored Javascript may be used to unknowingly execute web requests in the context of the user who is viewing the page. A factory reset is required to remove the stored Javascript.

CVE-2015-6488NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6488, web site last accessed December 08, 2015. has been assigned to this vulnerability. A CVSS v3 base score of 4.7 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N, web site last accessed October 27, 2015.

User input is not sufficiently sanitized, which may allow an attacker to create new users, delete users, or escalate privileges by getting an administrator to execute a specially crafted link.

CVE-2015-6486NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-6486, web site last accessed December 08, 2015. 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:L/UI:R/S:U/C:N/I:L/A:L).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:L, web site last accessed October 27, 2015.

VULNERABILITY DETAILS

EXPLOITABILITY

These vulnerabilities could be exploited remotely.

EXISTENCE OF EXPLOIT

No known public exploits specifically target these vulnerabilities.

DIFFICULTY

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

MITIGATION

Rockwell Automation has addressed the reported vulnerabilities in the Allen-Bradley MicroLogix 1100 controller, hardware Series B, in firmware Version 15.000. The identified vulnerabilities are not addressed in the Allen-Bradley MicroLogix 1100 controller, hardware Series A. Rockwell Automation recommends that asset owners using Series A controllers should implement the appropriate mitigations, which are discussed below.

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Rockwell Automation has addressed all the reported vulnerabilities, except the buffer overflow vulnerability, in the Allen-Bradley MicroLogix 1400 controllers, hardware Series B, firmware Version 15.003. The buffer overflow vulnerability in the Allen-Bradley MicroLogix 1400 controller, hardware Series B has been addressed in firmware Version 15.004.

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The identified vulnerabilities are not addressed in the Allen-Bradley MicroLogix 1400 controller, hardware Series A. Rockwell Automation recommends that asset owners using Series A controllers should implement the appropriate mitigations, which are discussed below.

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The firmware versions for the MicroLogix 1100 controller, hardware Series B, firmware Version 15.000 and the MicroLogix 1400 controller, hardware Series B, firmware Version 15.004 are available at the following URL:

http://compatibility.rockwellautomation.com/Pages/MultiProductDownload.aspx?famID=30&crumb=112

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Rockwell Automation’s security notification is available at the following URL, with a valid account:

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/732399

Rockwell Automation recommends that asset owners evaluate the impact with each of these vulnerabilities within their environment, and apply the following suggested mitigations, which are applicable.

• Update the supported products with the appropriate firmware update.
• Disable the web server on the MicroLogix 1100 and 1400, as it is enabled by default. See KB: 732398 for detailed instructions on disabling the web server for each controller platform. The Web Server Tech Note, KB: 732398 is available at the following URL, with a valid account:

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/732398

• Set the keyswitch to RUN to prohibit re-enabling of the web server via RSLogix 500.
• Use trusted software, software patches, antivirus/anti-malware programs and interact only with trusted web sites and attachments.
• Employ training and awareness programs to educate users on the warning signs of a phishing or social engineering attack.
• Rockwell recommends subscribing to the Security Advisory Index, which contains the Knowledgebase article KB: 54102 and provides the most up-to-date information about security matters that affect Rockwell Automation products. The Knowledgebase article is available at the following URL, with a valid account:

https://rockwellautomation.custhelp.com/app/answers/detail/a_id/54102

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.

In addition, ICS-CERT recommends that users take the following measures to protect themselves from social engineering attacks:

1. Do not click web links or open unsolicited attachments in email messages.
2. Refer to Recognizing and Avoiding Email ScamsRecognizing and Avoiding Email Scams, http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last accessed October 27, 2015. for more information on avoiding email scams.
3. Refer to Avoiding Social Engineering and Phishing AttacksNational Cyber Alert System Cyber Security Tip ST04-014, http://www.us-cert.gov/cas/tips/ST04-014.html, web site last accessed October 27, 2015. for more information on social engineering attacks.