As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global). 

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1. EXECUTIVE SUMMARY

CVSS v4 8.2
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Siemens
Equipment: RUGGEDCOM APE1808
Vulnerabilities: Cross-site Scripting, Improper Privilege Management, Improper Check for Unusual or Exceptional Conditions, Truncation of Security-relevant Information, Insufficient Session Expiration

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow a malicious administrator to store a JavaScript payload using the web interface, revoke active XML API keys from the firewall and disrupt XML API usage, or cause a denial-of-service.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Siemens RUGGEDCOM APE1808, an application hosting platform, are affected:

Siemens RUGGEDCOM APE1808: All versions with Palo Alto Networks Virtual NGFW configured with support for the CHACHA20-POLY1305 algorithm or any Encrypt-then-MAC algorithms (CVE-2023-48795)
Siemens RUGGEDCOM APE1808: All versions with Palo Alto Networks Virtual NGFW (CVE-2023-6789, CVE-2023-6793, CVE-2024-0008)
Siemens RUGGEDCOM APE1808: All versions with Palo Alto Networks Virtual NGFW that are configured with BGP routing features enabled (CVE-2023-38802)

3.2 Vulnerability Overview

3.2.1 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION (‘CROSS-SITE SCRIPTING’) CWE-79

A cross-site scripting (XSS) vulnerability in Palo Alto Networks PAN-OS software enables a malicious authenticated read-write administrator to store a JavaScript payload using the web interface. Then, when viewed by a properly authenticated administrator, the JavaScript payload executes and disguises all associated actions as performed by that unsuspecting authenticated administrator.

CVE-2023-6789 has been assigned to this vulnerability. A CVSS v3.1 base score of 4.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N).

A CVSS v4 score has also been calculated for CVE-2023-6789. A base score of 5.1 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N).

3.2.2 IMPROPER PRIVILEGE MANAGEMENT CWE-269

An improper privilege management vulnerability in Palo Alto Networks PAN-OS software enables an authenticated read-only administrator to revoke active XML API keys from the firewall and disrupt XML API usage.

CVE-2023-6793 has been assigned to this vulnerability. A CVSS v3.1 base score of 2.7 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L).

A CVSS v4 score has also been calculated for CVE-2023-6793. A base score of 5.1 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N).

3.2.3 IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONS CWE-754

FRRouting FRR 7.5.1 through 9.0 and Pica8 PICOS 4.3.3.2 allow a remote attacker to cause a denial of service via a crafted BGP update with a corrupted attribute 23 (Tunnel Encapsulation).

CVE-2023-38802 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.2.4 TRUNCATION OF SECURITY-RELEVANT INFORMATION CWE-222

The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted from the extension negotiation message. A client and server may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP) implemented by these extensions mishandles the handshake phase and mishandles use of sequence numbers.

CVE-2023-48795 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N).

A CVSS v4 score has also been calculated for CVE-2023-48795. A base score of 8.2 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N).

3.2.5 INSUFFICIENT SESSION EXPIRATION CWE-613

Web sessions in the management interface in Palo Alto Networks PAN-OS software do not expire in certain situations, making it susceptible to unauthorized access.

CVE-2024-0008 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.8 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:R/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

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

(CVE-2023-6789, CVE-2023-6793, CVE-2023-38802, CVE-2024-0008) RUGGEDCOM APE1808: Contact customer support to receive patch and update information.
(CVE-2023-48795) RUGGEDCOM APE1808: Currently no fix is available
(CVE-2023-48795) RUGGEDCOM APE1808: CVE-2023-48795: Customers can resolve this issue by configuring the in-use SSH profile to contain at least one cipher and at least one MAC algorithm, which removes support for CHACHA20-POLY1305 and all Encrypt-then-MAC algorithms available (ciphers with -etm in the name) in PAN-OS software. See Palo Alto Networks’ upstream documentation https://security.paloaltonetworks.com/CVE-2023-48795 for additional guidance.

As a general security measure, Siemens 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 Siemens’ operational guidelines for industrial security and following recommendations in the product manuals.

Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.

For more information see the associated Siemens security advisory SSA-455250 in HTML and CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:

Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more 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 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 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.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

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 these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

April 11, 2024: Initial Publication