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             AUSCERT External Security Bulletin Redistribution

                               ESB-2023.1709
        ICSA-23-080-04 Siemens RADIUS Client of SIPROTEC 5 Devices
                               22 March 2023

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           RADIUS client of SIPROTEC 5 devices
Publisher:         ICS-CERT
Operating System:  Network Appliance
Resolution:        Patch/Upgrade
CVE Names:         CVE-2022-38767  

Original Bulletin: 
   https://www.cisa.gov/news-events/ics-advisories/icsa-23-080-04

Comment: CVSS (Max):  7.5 CVE-2022-38767 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
         CVSS Source: ICS-CERT
         Calculator:  https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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ICS Advisory (ICSA-23-080-04)

Siemens RADIUS Client of SIPROTEC 5 Devices

Release Date
March 21, 2023

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) .

1. EXECUTIVE SUMMARY

  o CVSS v3 7.5
  o ATTENTION: Exploitable remotely/low attack complexity
  o Vendor: Siemens ProductCERT
  o Equipment: RADIUS client of SIPROTEC 5 devices
  o Vulnerability: Loop with Unreachable Exit Condition ('Infinite Loop')

2. RISK EVALUATION

The RADIUS client implementation of the VxWorks platform in SIPROTEC 5 devices
contains a denial-of-service vulnerability that could be triggered when a
specially crafted packet is sent by a RADIUS server.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following software from Siemens is affected:

  o SIPROTEC 5 6MD85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 6MD86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 6MD89 (CP300) - >= V7.80
  o SIPROTEC 5 6MU85 (CP300) - >= V7.90 < V9.30
  o SIPROTEC 5 7KE85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SA86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SA87 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SD86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SD87 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SJ85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SJ86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SK85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SL86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SL87 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7SS85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7ST85 (CP300) - >= V8.81 < V9.30
  o SIPROTEC 5 7ST86 (CP300) - >= V9.20 < V9.30
  o SIPROTEC 5 7SX85 (CP300) - >= V8.30 < V9.30
  o SIPROTEC 5 7UM85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7UT85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7UT86 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7UT87 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7VE85 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 7VK87 (CP300) - >= V7.80 < V9.30
  o SIPROTEC 5 Communication Module ETH-BA-2EL - >= V7.80 < V9.30
  o SIPROTEC 5 Communication Module ETH-BB-2FO - >= V7.80 < V9.30
  o SIPROTEC 5 Communication Module ETH-BD-2FO - >= V7.80 < V9.30
  o SIPROTEC 5 Compact 7SX800 (CP050) - >= V8.70 < V9.30

3.2 VULNERABILITY OVERVIEW

3.2.1 LOOP WITH UNREACHABLE EXIT CONDITION ('INFINITE LOOP') CWE-835  

An issue was discovered in Wind River VxWorks 6.9 and 7 that allows a
specifically crafted packet sent by a RADIUS server, which could cause a
denial-of-service condition during the IP Radius access procedure.

CVE-2022-38767 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:N/I:N/A:H ).

3.3 BACKGROUND

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

3.4 RESEARCHER

Siemens reported this vulnerability to CISA.

4. MITIGATIONS

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

  o SIPROTEC 5 6MD85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 6MD86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 6MD89 (CP300): Currently no fix is planned
  o SIPROTEC 5 6MU85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7KE85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SA86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SA87 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SD86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SD87 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SJ85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SJ86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SK85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SL86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SL87 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SS85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7ST85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7ST86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7SX85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7UM85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7UT85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7UT86 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7UT87 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7VE85 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 7VK87 (CP300): Update to V9.30 or later version
  o SIPROTEC 5 Communication Module ETH-BA-2EL: Update to V9.30 or later
    version
  o SIPROTEC 5 Communication Module ETH-BB-2FO: Update to V9.30 or later
    version
  o SIPROTEC 5 Communication Module ETH-BD-2FO: Update to V9.30 or later
    version
  o SIPROTEC 5 Compact 7SX800 (CP050): Update to V9.30 or later version
  o Protect the pre-shared key for RADIUS from unauthorized access
  o Ensure that only a trusted, properly hardened RADIUS server is configured
    in your environment

Operators of critical power systems (e.g. TSOs or DSOs) worldwide are usually
required by regulations to build resilience into the power grids by applying
multi-level redundant secondary protection schemes. It is therefore recommended
that the operators check whether appropriate resilient protection measures are
in place. The risk of cyber incidents impacting the grid's reliability can thus
be minimized by virtue of the grid design.

Siemens strongly recommends applying the provided security updates using the
corresponding tooling and documented procedures made available with the
product. If supported by the product, an automated means to apply the security
updates across multiple product instances may be used. Siemens strongly
recommends prior validation of any security update before being applied, and
supervision by trained staff of the update process in the target environment.
As a general security measure

Siemens strongly recommends users protect network access with appropriate
mechanisms (e.g. firewalls, segmentation, VPNs). It is advised to configure the
environment according to our operational guidelines to run the devices in a
protected IT environment. Recommended security guidelines can be found at the
Siemens webpage for grid security .

For further inquiries on security vulnerabilities in Siemens products and
solutions, users should contact the Siemens ProductCERT .

For more information, see the associated Siemens security advisory SSA-726834
in HTML and CSAF .

CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:

  o Minimize network exposure for all control system devices and/or systems,
    and ensure they are not accessible from the Internet .
  o Locate control system networks and remote devices behind firewalls and
    isolate them from business networks.
  o 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.

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

  o Do not click web links or open attachments in unsolicited email messages.
  o Refer to Recognizing and Avoiding Email Scams for more information on
    avoiding email scams.
  o Refer to Avoiding Social Engineering and Phishing Attacks for more
    information on social engineering attacks.

No known public exploits specifically target this vulnerability.

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