1. EXECUTIVE SUMMARY

CVSS v3 8.8
ATTENTION: Exploitable remotely/low attack complexity 
Vendor: SAUTER 
Equipment: EY-modulo 5 Building Automation Stations 
Vulnerabilities: Cross-site Scripting, Cleartext Transmission of Sensitive Information, and Unrestricted Upload of File with Dangerous Type 

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could lead to privilege escalation, unauthorized execution of actions, a denial-of-service condition, or retrieval of sensitive information. 

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

SAUTER reports these vulnerabilities affect the following EY-modulo 5 Building Automation Stations:  

EY-AS525F001 with moduWeb 

3.2 VULNERABILITY OVERVIEW

3.2.1 CROSS-SITE SCRIPTING CWE-79 

An unauthenticated remote attacker could provide a malicious link and trick an unsuspecting user into clicking on it. If clicked, the attacker could execute the malicious JavaScript (JS) payload in the target’s security context. 

CVE-2023-28650 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). 

3.2.2 CROSS-SITE SCRIPTING CWE-79 

A malicious user could leverage this vulnerability to escalate privileges or perform unauthorized actions in the context of the targeted privileged users. 

CVE-2023-28655 has been assigned to this vulnerability. A CVSS v3 base score of 8.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H). 

3.2.3 CROSS-SITE SCRIPTING CWE-79 

An unauthenticated remote attacker could force all authenticated users, such as administrative users, to perform unauthorized actions by viewing the logs. This action would also grant the attacker privilege escalation. 

CVE-2023-22300 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). 

3.2.4 CLEARTEXT TRANSMISSION OF SENSITIVE INFORMATION CWE-319 

An authenticated malicious user could acquire the simple mail transfer protocol (SMTP) Password in cleartext format, despite it being protected and hidden behind asterisks. The attacker could then perform further attacks using the SMTP credentials. 

CVE-2023-27927 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N). 

3.2.5 UNRESTRICTED UPLOAD OF FILE WITH DANGEROUS TYPE CWE-434 

An authenticated malicious user could successfully upload a malicious image could lead to a denial-of-service condition. 

CVE-2023-28652 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). 

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Energy 
COUNTRIES/AREAS DEPLOYED: Worldwide 
COMPANY HEADQUARTERS LOCATION: Switzerland 

3.4 RESEARCHER

Ithaca Labs of Odyssey Cyber Security reported this vulnerability to CISA. 

4. MITIGATIONS

According to SAUTER, the EY-modulo 5 Building Automation Stations product line does not support encryption on its communication protocols. As such, it is not appropriate for open networks.  

SAUTER recommends deactivating moduWeb when not in use as doing so closes the vulnerabilities related to the web server and the mail client service; users can upgrade to the latest generation modulo 6 with moduWeb Unity as the web server, which supports encrypted communication with TLS. 

SAUTER recommends users take all necessary measures to protect the integrity of building automation networks, restrict access to the devices, and leverage all appropriate means and policies to minimize risks. Users should evaluate and upgrade legacy systems to current solutions where necessary. 

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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 exploits specifically target these vulnerabilities. These vulnerabilities are exploitable remotely. These vulnerabilities have low attack complexity.