1. EXECUTIVE SUMMARY
- CVSS v3 7.5
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: GE Gas Power
- Equipment: ToolBoxST
- Vulnerabilities: Improper Restriction of XML External Entity Reference, Path Traversal
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could result in data exfiltration or arbitrary write, overwrite, and execution.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
GE reports these vulnerabilities affect the following software platform for programming:
- ToolBoxST OS: All versions prior to 07.09.07C
3.2 VULNERABILITY OVERVIEW
GE Gas Power ToolBoxST Version v04.07.05C suffers from an XML external entity (XXE) vulnerability using the DTD parameter entities technique that could result in disclosure and retrieval of arbitrary data on the affected node via an out-of-band (OOB) attack. The vulnerability is triggered when input passed to the XML parser is not sanitized while parsing the XML project/template file.
ToolBoxST prior to Version 7.8.0 uses a vulnerable version of the Ionic .NET Zip library that does not properly sanitize path names allowing files to be extracted to a location above their parent directory and back to the root directory. If an attacker compromises an HMI or creates their own SDI client, they can upload the device.zip file from a controller, patch it to contain a malicious file and path, and download it back to the controller. The next user to perform an upload could grab the malicious device.zip and extract it to their HMI, creating the potential for arbitrary write, overwrite, and execution.
- CRITICAL INFRASTRUCTURE SECTORS: Communications, Critical Manufacturing, Energy, Healthcare and Public Health, Transportation Systems, Water and Wastewater Systems
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: United States
Sharon Briznov of Claroty reported these vulnerabilities to GE.
GE addressed CVE-2021-44477 in ToolBoxST OS Version 07.09.07C and above by disabling the use of DTD’s, which are not necessary for ToolBoxST functionality.
GE upgraded the Ionic library in ToolBoxST Version 7.8.0 to resolve CVE-2018-16202
Users should ensure they follow the password protection and network segmentation guidance laid out in GEH-6839 Secure Deployment Guide. Additionally, the use of SDI Secure Mode offers considerable protection against this attack as the threat actor must be able to perform a download to the controller over SDI. Secure Mode validates authenticity and protects against spoofing of SDI commands.
GE Gas Power Cybersecurity and Engineering teams will continue to investigate internally as well as monitor industry-based news for any changes or updates. To reduce the risk vulnerabilities such as these may represent to the controls network, GE recommends the implementation of a good defense-in-depth strategy as detailed in GEH-6839. Some recommended controls include:
- Minimize network exposure for all controllers with the use of network segmentation, placement of controllers behind controls network firewalls and ensure they are not accessible from the Internet.
- Block suspicious external IP addresses at the controls network firewalls. Monitor traffic internally for unusual behavior.
- 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.
- Implement defense-in-depth within the controls network environment consisting of tools such as Intrusion detection/prevention systems (IDS/IPS), firewalls, and network access control (NAC).
- Implement and maintain an anti-malware solution and an endpoint detection and response (EDR) solution.
- Disable remote access services and protocols such as remote desktop protocol (RDP) unless needed. Monitor and restrict remote access usage on a least-privilege basis.
- Have backup and restore processes and procedures in place for disaster recovery and incident response.
- Monitor and maintain account provisioning and access control based on the principle of least privilege.
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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. 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 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.
CISA also recommends users take the following measures to protect themselves from social engineering attacks:
- Do not click web links or open unsolicited attachments in email messages.
- Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
- Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.
No known public exploits specifically target these vulnerabilities.