Siemens SCALANCE X Switches Use of Hard-Coded Cryptographic Key (CVE-2020-28391)

medium Tenable OT Security Plugin ID 500783

Synopsis

The remote OT asset is affected by a vulnerability.

Description

A vulnerability has been identified in SCALANCE X-200 switch family (incl. SIPLUS NET variants) (All versions < V5.2.5), SCALANCE X-200IRT switch family (incl. SIPLUS NET variants) (All versions < V5.5.0), SCALANCE X-200RNA switch family (All versions < V3.2.7). 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.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at CISA.gov.

Siemens recommends applying updates where available:

- SCALANCE X-200 switch family (incl. SIPLUS NET variants): Update to v5.2.5 or later

- SCALANCE X-200RNA switch family: Update to v3.2.7 or later

- SCALANCE X-300 switch family (incl. X408 and SIPLUS NET variants): Update to v4.1.0 or later
- SCALANCE X-200IRT switch family (incl. SIPLUS NET variants): Update to v5.5.0 or later

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

- Update the default self-signed device X.509 certificates with own trusted certificate.
- 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)

As a general security measure, Siemens strongly 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 the Siemens operational guidelines for Industrial Security and following the recommendations in the product manuals.

For additional information, please refer to Siemens Security Advisory SSA-274900

Plugin Details

Severity: Medium

ID: 500783

Version: 1.7

Type: remote

Family: Tenable.ot

Published: 1/25/2023

Updated: 9/4/2024

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:N

CVSS Score Source: CVE-2020-28391

CVSS v3

Risk Factor: Medium

Base Score: 5.9

Temporal Score: 5.2

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:siemens:scalance_x200_firmware, cpe:/o:siemens:scalance_x200rna_firmware, cpe:/o:siemens:scalance_x408_firmware, cpe:/o:siemens:scalance_x300_firmware, cpe:/o:siemens:scalance_x200irt_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 1/12/2021

Vulnerability Publication Date: 1/12/2021

Reference Information

CVE: CVE-2020-28391

CWE: 321

ICSA: 21-012-02

Detections

Analytics