SSA-274900

Siemens Security Advisory by Siemens ProductCERT

SSA-274900: Use of Hardcoded Key in SCALANCE X Devices Under Certain Conditions

Publication Date:	2021-01-12
Last Update:	2022-12-13
Current Version:	V1.3
CVSS v3.1 Base Score:	9.1

SUMMARY

SCALANCE X devices might not generate a unique random key after factory reset, and use a private key shipped with the firmware.

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

AFFECTED PRODUCTS AND SOLUTION

Affected Product and Versions	Remediation
SCALANCE X-200 switch family (incl. SIPLUS NET variants) All versions < V5.2.5 only affected by CVE-2020-28391	Update to V5.2.5 or later version https://support.industry.siemens.com/cs/ww/en/view/109801131/ See further recommendations from section Workarounds and Mitigations
SCALANCE X-200IRT switch family (incl. SIPLUS NET variants) All versions < V5.5.0 only affected by CVE-2020-28391	Update to V5.5.0 or later version https://support.industry.siemens.com/cs/ww/en/view/109792534/ See further recommendations from section Workarounds and Mitigations
SCALANCE X-200RNA switch family All versions < V3.2.7	Update to V3.2.7 or later version https://support.industry.siemens.com/cs/ww/en/view/109814809/ See further recommendations from section Workarounds and Mitigations
SCALANCE X-300 switch family (incl. X408 and SIPLUS NET variants) All versions < V4.1.0 only affected by CVE-2020-28395	Update to V4.1.0 or later version (for supported devices) https://support.industry.siemens.com/cs/ww/en/view/109773547/ See further recommendations from section Workarounds and Mitigations

WORKAROUNDS AND MITIGATIONS

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

Update the default selfsigned device X.509 certificates with own trusted certificates
Update the default hardcoded X.509 certificates from the firmware image (fingerprints SHA-1: F2:C8:3B:8F:86:27:74:AA:60:EC:D4:A0:CF:0D:BE:A6:D1:FE:22:12 and SHA-256: 25:60:DB:B3: F9:07:9D:69:0E:DD:A9:EB:4E:1C:D5:8E:AF:79:16:C3:C8:13:A6:F6:59:AD:05:E4:6F:77:F7:72 - fingerprints for X-200RNA switch devices SHA-1: 04:64:EF:98:A4:42:D2:BB:57:4A:47:12:20:EC:E6:85:15:4F:03:61 and SHA-256: 9C:15:FA:56:ED:FF:CA:8D:17:16:E9:2C:57:CB:90:3C:4E:81:5B:3D:60:E9:CF:26:07:B3:73:F6:C7:02:75:88)

Product-specific remediations or mitigations can be found in the section Affected Products and Solution.
Please follow the General Security Recommendations.

GENERAL SECURITY RECOMMENDATIONS

As a general security measure, Siemens strongly recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens' operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals.

Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity

PRODUCT DESCRIPTION

SCALANCE X switches are used to connect industrial components like Programmable Logic Controllers (PLCs) or Human Machine Interfaces (HMIs).

SIPLUS extreme products are designed for reliable operation under extreme conditions and are based on SIMATIC, LOGO!, SITOP, SINAMICS, SIMOTION, SCALANCE or other devices. SIPLUS devices use the same firmware as the product they are based on.

VULNERABILITY CLASSIFICATION

The vulnerability classification has been performed by using the CVSS scoring system in version 3.1 (CVSS v3.1) (https://www.first.org/cvss/). The CVSS environmental score is specific to the customer’s environment and will impact the overall CVSS score. The environmental score should therefore be individually defined by the customer to accomplish final scoring.

An additional classification has been performed using the CWE classification, a community-developed list of common software security weaknesses. This serves as a common language and as a baseline for weakness identification, mitigation, and prevention efforts. A detailed list of CWE classes can be found at: https://cwe.mitre.org/.

Vulnerability CVE-2020-28391

Devices create a new unique key upon factory reset, except when used with C-PLUG. When used with C-PLUG the devices use the hardcoded private RSA-key shipped with the firmware-image. An attacker could leverage this situation to a man-in-the-middle situation and decrypt previously captured traffic.

CVSS v3.1 Base Score	9.1
CVSS Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:P/RL:U/RC:C
CWE	CWE-321: Use of Hard-coded Cryptographic Key

Vulnerability CVE-2020-28395

Devices do not create a new unique private key after factory reset. An attacker could leverage this situation to a man-in-the-middle situation and decrypt previously captured traffic.

CVSS v3.1 Base Score	9.1
CVSS Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:P/RL:U/RC:C
CWE	CWE-321: Use of Hard-coded Cryptographic Key

ADDITIONAL INFORMATION

These vulnerabilities have been discovered internally by Siemens.

For further inquiries on security vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT:

https://www.siemens.com/cert/advisories

HISTORY DATA

V1.0 (2021-01-12):	Publication Date
V1.1 (2021-02-09):	Added update information for SCALANCE X-200IRT switch family
V1.2 (2021-09-14):	Added solution for SCALANCE X-200 switch family
V1.3 (2022-12-13):	Added SCALANCE X-200RNA switch family

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