CISA Advisory: Subnet Solutions PowerSYSTEM Center | CISA

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1. EXECUTIVE SUMMARY

• CVSS v3 9.8
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Subnet Solutions
• Equipment: PowerSYSTEM Center
• Vulnerabilities: Improper Restriction of XML External Entity Reference, Integer Overflow or Wraparound

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to cause an integer overflow on the affected device.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SUBNET PowerSYSTEM Center, an OT device management platform, are affected:

• PowerSYSTEM Center PSC 2020: v5.22.x and prior

3.2 Vulnerability Overview

3.2.1 Improper Restriction of XML External Entity Reference CWE-611

An issue was discovered in libexpat before 2.6.3. xmlparse.c does not reject a negative length for XML_ParseBuffer.

CVE-2024-45490 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.2.2 Integer Overflow or Wraparound CWE-190

An issue was discovered in libexpat before 2.6.3. dtdCopy in xmlparse.c can have an integer overflow for nDefaultAtts on 32-bit platforms (where UINT_MAX equals SIZE_MAX).

CVE-2024-45491 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.2.3 Integer Overflow or Wraparound CWE-190

An issue was discovered in libexpat before 2.6.3. nextScaffoldPart in xmlparse.c can have an integer overflow for m_groupSize on 32-bit platforms (where UINT_MAX equals SIZE_MAX).

CVE-2024-45492 has been assigned to this vulnerability. A CVSS v3.1 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

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

3.4 RESEARCHER

Subnet Solutions Inc. reported these vulnerabilities to CISA

4. MITIGATIONS

Subnet Solutions inc. reports that dependencies have been updated and vulnerabilities are to be addressed in PowerSYSTEM Center 2020 Update 23 release.

Subnet Solutions Inc. strongly recommends users update to the latest version. If this is not possible, the following mitigations have been identified:

• Apply application allow-listing to prevent unauthorized executables from running.
• Ensure Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) are enabled within the operating system. Memory protection controls can be enabled via Windows Security. Please refer to this article for reference.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:

• Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
• Locate control system networks and remote devices behind firewalls and isolating them from business networks.
• When remote access is required, use more 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 the 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 cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

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

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

• November 12, 2024: Initial Publication