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AUSCERT External Security Bulletin Redistribution
ESB-2021.0504
Advisory (icsa-21-040-10) Siemens DIGSI 4
11 February 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens DIGSI 4
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Increased Privileges -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-25245
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-040-10
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ICS Advisory (ICSA-21-040-10)
Siemens DIGSI 4
Original release date: February 09, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.8
o ATTENTION: Low skill level to exploit
o Vendor: Siemens
o Equipment: DIGSI 4
o 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:
o 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
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o 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:
o DIGSI 4: Update to v4.94 SP1 HF 1 or later version
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:
o Do not click web links or open unsolicited attachments in 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.
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.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
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