ICS Advisory (ICSA-21-040-10)

Siemens DIGSI 4

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.8
  • ATTENTION: Low skill level to exploit
  • Vendor: Siemens
  • Equipment: DIGSI 4
  • Vulnerability: Incorrect Default Permissions

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow a low privileged attacker to execute arbitrary code with SYSTEM privileges.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following Siemens products are affected:

  • DIGSI 4: All versions prior to v4.94 SP1 HF 1

3.2 VULNERABILITY OVERVIEW

3.2.1    INCORRECT DEFAULT PERMISSIONS CWE-276

Several folders in the %PATH% are writeable by normal users. As these folders are included in the search for DLLs, an attacker could place a DLL file with code executed by SYSTEM.

CVE-2020-25245 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:L/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Rich Davy from ECSC Group reported this vulnerability to Siemens.

4. MITIGATIONS

Siemens has released updates, which are recommended to be applied when possible:

As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens’ operational guidelines for industrial security, and follow the recommendations in the product manuals.

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

For more information see Siemens security advisory SSA-536315

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


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.


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://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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