1. EXECUTIVE SUMMARY
- CVSS v3 9.9
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: Siemens
- Equipment: SIMATIC CN 4100
- Vulnerabilities: Improper Access Control, Incorrect Default Permissions
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow an attacker to gain privilege escalation and bypass network isolation.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Siemens SIMATIC CN 4100, a communication node, are affected:
- SIMATIC CN 4100: all versions prior to V2.5
3.2 VULNERABILITY OVERVIEW
Affected device consists of improper access controls in the configuration files that could lead to privilege escalation. An attacker could gain admin access with this vulnerability, leading to complete device control.
Affected device consists of an incorrect default value in the SSH configuration. This could allow an attacker to bypass network isolation.
Michael Klassen and Martin Floeck of BASF Security Team reported these vulnerabilities to Siemens.
Siemens identified the following specific workarounds and mitigations users can apply to reduce risk:
- SIMATIC CN 4100: Update to V2.5 or later version.
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for industrial security and following recommendations in the product manuals.
CISA recommends 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 they are not accessible from the Internet.
- Locate control system networks and remote devices behind firewalls and isolate them from business networks.
- 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 at 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.
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 exploits specifically target these vulnerabilities.