Siemens Remote Connect Server

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 9.6
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Siemens
• Equipment: Remote Connect Server
• Vulnerabilities: Incorrect User Management, Unrestricted Upload of File with Dangerous Type, Forced Browsing, Improper Check for Unusual or Exceptional Conditions, Client-Side Enforcement of Server-Side Security, Incorrect Authorization, Creation of Temporary File With Insecure Permissions, Improper Restriction of Excessive Authentication Attempts, Incorrect Permission Assignment for Critical Resource, Allocation of Resources Without Limits or Throttling

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of service condition, learn vulnerable credentials, escalate privileges, modify users outside of scope, gain access to participant groups, use temporary credentials for authentication bypass, or execute arbitrary code.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following products of Siemens, are affected:

• Siemens SINEMA Remote Connect Server: All versions prior to V3.2 SP1

3.2 Vulnerability Overview

3.2.1 INCORRECT USER MANAGEMENT CWE-286

The affected application creates temporary user credentials for UMC (User Management Component) users. An attacker could use these temporary credentials for authentication bypass in certain scenarios.

CVE-2022-32260 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H).

3.2.2 UNRESTRICTED UPLOAD OF FILE WITH DANGEROUS TYPE CWE-434

The affected application allows users to upload encrypted backup files. As part of this backup, files can be restored without correctly checking the path of the restored file. This could allow an attacker with access to the backup encryption key to upload malicious files, that could potentially lead to remote code execution.

CVE-2024-39865 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.2.3 PRIVILEGE DEFINED WITH UNSAFE ACTIONS CWE-267

The affected application allows users to upload encrypted backup files. This could allow an attacker with access to the backup encryption key and with the right to upload backup files to create a user with administrative privileges.

CVE-2024-39866 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.2.4 DIRECT REQUEST ('FORCED BROWSING') CWE-425

Affected devices do not properly validate the authentication when performing certain actions in the web interface allowing an unauthenticated attacker to access and edit device configuration information of devices for which they have no privileges.

CVE-2024-39867 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H).

3.2.5 DIRECT REQUEST ('FORCED BROWSING') CWE-425

Affected devices do not properly validate the authentication when performing certain actions in the web interface allowing an unauthenticated attacker to access and edit VxLAN configuration information of networks for which they have no privileges.

CVE-2024-39868 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H).

3.2.6 IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONS CWE-754

Affected products allow to upload certificates. An authenticated attacker could upload a crafted certificates leading to a permanent denial-of-service situation. In order to recover from such an attack, the offending certificate needs to be removed manually.

CVE-2024-39869 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

3.2.7 CLIENT-SIDE ENFORCEMENT OF SERVER-SIDE SECURITY CWE-602

The affected applications can be configured to allow users to manage own users. A local authenticated user with this privilege could use this modify users outside of their own scope as well as to escalate privileges.

CVE-2024-39870 has been assigned to this vulnerability. A CVSS v3 base score of 6.3 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).

3.2.8 INCORRECT AUTHORIZATION CWE-863

Affected applications do not properly separate the rights to edit device settings and to edit settings for communication relations. This could allow an authenticated attacker with the permission to manage devices to gain access to participant groups that the attacked does not belong to.

CVE-2024-39871 has been assigned to this vulnerability. A CVSS v3 base score of 6.3 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).

3.2.9 CREATION OF TEMPORARY FILE WITH INSECURE PERMISSIONS CWE-378

The affected application does not properly assign rights to temporary files created during its update process. This could allow an authenticated attacker with the 'Manage firmware updates' role to escalate their privileges on the underlying OS level.

CVE-2024-39872 has been assigned to this vulnerability. A CVSS v3 base score of 9.6 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N).

3.2.10 IMPROPER RESTRICTION OF EXCESSIVE AUTHENTICATION ATTEMPTS CWE-307

The affected application does not properly implement brute force protection against user credentials in its web API. This could allow an attacker to learn user credentials that are vulnerable to brute force attacks.

CVE-2024-39873 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.11 IMPROPER RESTRICTION OF EXCESSIVE AUTHENTICATION ATTEMPTS CWE-307

The affected application does not properly implement brute force protection against user credentials in its Client Communication component. This could allow an attacker to learn user credentials that are vulnerable to brute force attacks.

CVE-2024-39874 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.12 INCORRECT PERMISSION ASSIGNMENT FOR CRITICAL RESOURCE CWE-732

The affected application allows authenticated, low privilege users with the 'Manage own remote connections' permission to retrieve details about other users and group memberships.

CVE-2024-39875 has been assigned to this vulnerability. A CVSS v3 base score of 4.3 has been assigned; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

3.2.13 ALLOCATION OF RESOURCES WITHOUT LIMITS OR THROTTLING CWE-770

Affected applications do not properly handle log rotation. This could allow an unauthenticated remote attacker to cause a denial of service condition through resource exhaustion on the device.

CVE-2024-39876 has been assigned to this vulnerability. A CVSS v3 base score of 4.0 has been assigned; the CVSS vector string is (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Energy, Nuclear Reactors, Materials, and Waste
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

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

• SINEMA Remote Connect Server: Update to V3.2 SP1 or later version

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-381581 in HTML and CSAF.

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). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are 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. 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 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.

CISA also recommends users take the following measures to protect themselves from social engineering attacks:

• Do not click web links or open attachments in unsolicited 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 exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

• July 11, 2024: Initial Publication

• Siemens