As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).

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1. EXECUTIVE SUMMARY

CVSS v3 7.5
ATTENTION: Exploitable remotely
Vendor: Siemens
Equipment: SICAM A8000
Vulnerability: Path Traversal

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to traverse directories, download arbitrary files, or escalate privileges.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Siemens SICAM A8000, a remote terminal unit, are affected:

CP-8031 MASTER MODULE (6MF2803-1AA00): All versions prior to CPCI85 V05.11
CP-8050 MASTER MODULE (6MF2805-0AA00): All versions prior to CPCI85 V05.11

3.2 Vulnerability Overview

3.2.1 Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’) CWE-22

The web server of affected devices fails to properly sanitize user input for the /sicweb-ajax/tmproot/ endpoint. This could allow an authenticated remote attacker to traverse directories on the system and download arbitrary files. By exploring active session IDs, the vulnerability could potentially be leveraged to escalate privileges to the administrator role.

CVE-2023-42796 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Multiple
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Meta reported this vulnerability to Siemens.

4. MITIGATIONS

Siemens has released updates for the affected products and recommends users update to the latest versions.:

Update to CPCI85 V05.11 or later version

Siemens has identified the following specific workarounds and mitigations that customers can apply to reduce the risk:

Restrict network access to the integrated web server.
Review the list of users that are allowed to log in to the integrated web server and apply strong passwords.

As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. 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.

Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.

For more information see the associated Siemens security advisory SSA-770890 in HTML and CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, 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 this vulnerability has been reported to CISA at this time. This vulnerability has a high attack complexity.

5. UPDATE HISTORY

October 12, 2023: Initial Publication