Siemens LOGO! Soft Comfort (Update A)

1. EXECUTIVE SUMMARY

• CVSS v3 7.8
• ATTENTION: Low skill level to exploit
• Vendor: Siemens
• Equipment: LOGO! Soft Comfort
• Vulnerability: Deserialization of Untrusted Data

2. UPDATE INFORMATION

This updated advisory is a follow-up to the original advisory titled ICSA-19-134-03 Siemens LOGO! Soft Comfort that was published May 14, 2019, on the ICS webpage on us-cert.cisa.gov.

3. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code if the attacker tricks a legitimate user into opening a manipulated project.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

Siemens reports the vulnerability affects the following engineering software to configure and program LOGO! controllers: 

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• LOGO! Soft Comfort: All versions prior to v8.3

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4.2 VULNERABILITY OVERVIEW

4.2.1    DESERIALIZATION OF UNTRUSTED DATA CWE-502

The vulnerability could allow an attacker to execute arbitrary code if the attacker tricks a legitimate user into opening a manipulated project. To exploit the vulnerability, a valid user must open a manipulated project file. 

CVE-2019-10924 has been assigned to this vulnerability. A CVSS v3 base score of 7.8 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

4.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Transportation Systems
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

4.4 RESEARCHER

Axt, working with iDefense Labs, reported this vulnerability to Siemens.

5. MITIGATIONS

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Siemens has released update v8.3 for the LOGO! Soft Comfort and recommends users update to the latest version.

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Siemens recommends users only open projects from trusted sources.

As a general security measure, Siemens strongly 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 the recommendations in the product manuals.

For more information on this vulnerability and associated software updates, please see Siemens security advisory SSA-102144

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

• Do not click web links or open unsolicited attachments in 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.

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.cisa.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.cisa.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 this vulnerability. This vulnerability is not exploitable remotely.

• Siemens