1. EXECUTIVE SUMMARY

CVSS v3 9.6
ATTENTION: Exploitable remotely/low attack complexity 
Vendor: CODESYS, GmbH 
Equipment: CODESYS Development System 
Vulnerability: Insufficient Verification of Data Authenticity. 

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to execute a-man-in-the-middle (MITM) attack to execute arbitrary code. 

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

CODESYS reports this vulnerability affects the following versions of CODESYS Development System: 

CODESYS Development System: versions from 3.5.11.0 and prior to 3.5.19.20 

3.2 VULNERABILITY OVERVIEW

3.2.1 INSUFFICIENT VERIFICATION OF DATA AUTHENTICITY CWE-345 

In CODESYS Development System versions from 3.5.11.0 and before 3.5.19.20 a missing integrity check might allow an unauthenticated remote attacker to manipulate the content of notifications received via HTTP by the CODESYS notification server. 

CVE-2023-3663 has been assigned to this vulnerability. A CVSS v3 base score of 9.6 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:C/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

Sina Kheirkhah of Summoning Team working with Trend Micro Zero Day Initiative reported this vulnerability. CERT@VDE coordinated the vulnerability. 

4. MITIGATIONS

CODESYS recommends users update the CODESYS Development System to version 3.5.19.20. 

The CODESYS Development System can be downloaded and installed directly with the CODESYS Installer or be downloaded from the CODESYS Store. 

Alternatively, users may find further information on obtaining the software update in the CODESYS Update area. 

For more information, please see the advisory CERT@VDE published for CODESYS at: 

https://cert.vde.com/en-us/advisories/vde-2023-022 

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should: 

Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the Internet. 
Locate control system networks and remote devices behind firewalls and isolate them from business networks. 
When remote access is required, use secure methods, such as virtual private networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its 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 at cisa.gov/ics. Several CISA products detailing cyber defense best 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 at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies. 

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

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

Do not click web links or open attachments in unsolicited 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. 

No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time.