ICS Advisory (ICSA-20-042-10)

Siemens SCALANCE S-600

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely
  • Vendor: Siemens
  • Equipment: SCALANCE S-600 Firewall
  • Vulnerabilities: Resource Exhaustion, Cross-site Scripting

2. RISK EVALUATION

These vulnerabilities could allow a remote attacker to conduct denial-of-service or cross-site scripting attacks. User interaction is required for a successful exploitation of the cross-site-scripting attack.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SCALANCE S-600, are affected:

  • SCALANCE S602, all versions v3.0 or higher
  • SCALANCE S612, all versions v3.0 or higher
  • SCALANCE S623, all versions v3.0 or higher
  • SCALANCE S627-2M, all versions v3.0 or higher

3.2 VULNERABILITY OVERVIEW

3.2.1    CROSS-SITE SCRIPTING CWE-80

The integrated configuration web server of the affected devices could allow cross-site scripting (XSS) attacks if unsuspecting users are tricked into accessing a malicious link.

CVE-2019-6585 has been assigned to this vulnerability. A CVSS v3 base score of 4.7 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N).

3.2.2    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

Specially crafted packets sent to Port 443/TCP of affected devices could cause a denial-of-service condition of the web server.

CVE-2019-13925 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.3    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

Specially crafted packets sent to Port 443/TCP of affected devices could cause a denial-of-service condition of the web server. A cold reboot is required to restore the functionality of the device.

CVE-2019-13926 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Information Technology
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Melih Berk Ekşioğlu reported some of these vulnerabilities to Siemens.

4. MITIGATIONS

For SCALANCE S602 v3.0, Siemens recommends only accessing links from trusted sources in the browser you use to access the SCALANCE S administration website.

For SCALANCE S612, all versions v3.0 or higher, SCALANCE S623, all versions v3.0 or higher, and SCALANCE S627-2M, all versions v3.0 or higher, Siemens recommends migrating to SCALANCE SC-600 Industrial Security Appliances.

For more information on these vulnerabilities and associated software updates, please see Siemens security advisory SSA-591405

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. Specifically, users should take the following measures to protect themselves from social engineering attacks: 

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 us-cert.gov. Several recommended 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 on us-cert.gov in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.


Contact Information

For any questions related to this report, please contact the CISA at:

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://www.us-cert.gov/ics 
or incident reporting:  https://www.us-cert.gov/report

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