Honeywell Experion PKS and ACE Controllers

1. EXECUTIVE SUMMARY

• CVSS v3 10.0 ***ATTENTION: **Exploitable remotely/low attack complexity
• **Vendor:**Honeywell
• Equipment: Experion Process Knowledge System (PKS) C200, C200E, C300 and ACE Controllers
• Vulnerabilities: Unrestricted Upload of File with Dangerous Type, Relative Path Traversal, Improper Neutralization of Special Elements in Output Used by a Downstream Component

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could lead to remote code execution and denial-of-service conditions.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Experion PKS, a process control system, are affected:

• C200: All versions
• C200E: All versions
• C300 and ACE controllers: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1 UNRESTRICTED UPLOAD OF FILE WITH DANGEROUS TYPE CWE-434

The affected product is vulnerable to unrestricted file uploads, which may allow an attacker to remotely execute arbitrary code and cause a denial-of-service condition.

CVE-2021-38397 has been assigned to this vulnerability. A CVSS v3 base score of 10.0 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H).

3.2.2 IMPROPER NEUTRALIZATION OF SPECIAL ELEMENTS IN OUTPUT USED BY A DOWNSTREAM COMPONENT CWE-74

The affected product is vulnerable to improper neutralization of special elements in output, which may allow an attacker to remotely execute arbitrary code and cause a denial-of-service condition.

CVE-2021-38395 has been assigned to this vulnerability. A CVSS v3 base score of 9.1 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H).

3.2.3 RELATIVE PATH TRAVERSAL CWE-23

The affected product is vulnerable to relative path traversal, which may allow an attacker access to unauthorized files and directories.

CVE-2021-38399 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:H/I:N/A:N).

3.3 BACKGROUND

• **CRITICAL INFRASTRUCTURE SECTORS:**Critical Manufacturing
• COUNTRIES/AREAS DEPLOYED: Worldwide
• **COMPANY HEADQUARTERS LOCATION:**Canada

3.4 RESEARCHER

Rei Henigman and Nadav Erez of Claroty reported these vulnerabilities to CISA.

4. MITIGATIONS

Honeywell recommends users follow all guidance in the Experion Network and Security Planning Guide to prevent attacks by malicious actors.

Additional information can be found in Honeywell Support document SN2021-02-22-01.

CISA 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 VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

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

CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.cisa.gov. 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 webpage on us-cert.cisa.gov 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 CISA for tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.