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AUSCERT External Security Bulletin Redistribution
ESB-2020.2399
Advisory (icsa-20-196-08) Siemens LOGO! Web Server
15 July 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens LOGO! Web Server
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2020-7593
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-20-196-08
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ICS Advisory (ICSA-20-196-08)
Siemens LOGO! Web Server
Original release date: July 14, 2020
Legal Notice
All information products included in https://us-cert.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://www.us-cert.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 9.8
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Siemens
o Equipment: LOGO! Web Server
o Vulnerability: Classic Buffer Overflow
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow remote code
execution.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of LOGO! Web Server are affected:
o LOGO! 8 BM (incl. SIPLUS variants):
Versions between 1.81.01 and 1.81.03
Version 1.82.01
Version 1.82.02
3.2 VULNERABILITY OVERVIEW
3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW')
CWE-120
A buffer overflow vulnerability in the Web Server functionality of the device
allows an unauthenticated attacker to send specially crafted HTTP requests,
which may cause memory corruption and result in remote code execution.
CVE-2020-7593 has been assigned to this vulnerability. A CVSS v3 base score of
9.8 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/
C:H/I:H/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Energy, Food and Agriculture,
Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
Alexander Perez-Palma and Dave McDaniel from Cisco Talos and Emanuel Almeida
from Cisco Systems reported this vulnerability to Siemens.
4. MITIGATIONS
Siemens recommends affected users update to the following versions:
LOGO! 8 BM (incl.SIPLUS varriants):
o Versions between 1.81.01 and 1.81.03: Update to v1.81.04
o Version 1.82.01: Update to v1.82.03
o Version 1.82.02: Update to v1.82.04
Siemens recommends applying defense-in-depth concepts, including the protection
concept outlined in the system manual.
Siemens recommends following their general security recommendations. 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 the
Siemens operational guidelines for Industrial Security and following the
recommendations in the product manuals.
For additional information, please refer to Siemens Security Advisory
SSA-573753 .
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 that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should
be updated to the most current version available. Also recognize that VPN
is only as secure as the 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 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 this vulnerability.
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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