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 8.7
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Siemens
Equipment: RUGGEDCOM APE1808
Vulnerabilities: Heap-based Buffer Overflow, External Control of File Name or Path, Improper Privilege Management, Uncontrolled Resource Consumption, Improper Certificate Validation, Out-of-bounds Write, Use of Externally-Controlled Format String

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to execute elevated actions, cause a denial-of-service, or execute arbitrary commands or code.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

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

RUGGEDCOM APE1808: All versions with Fortinet NGFW

3.2 Vulnerability Overview

3.2.1 HEAP-BASED BUFFER OVERFLOW CWE-122

A heap-based buffer overflow vulnerability in the SOCKS5 proxy handshake in the Curl package. If Curl is unable to resolve the address itself, it passes the hostname to the SOCKS5 proxy. However, the maximum length of the hostname that can be passed is 255 bytes. If the hostname is longer, then Curl switches to the local name resolving and passes the resolved address only to the proxy. The local variable that instructs Curl to “let the host resolve the name” could obtain the wrong value during a slow SOCKS5 handshake, resulting in the too-long hostname being copied to the target buffer instead of the resolved address, which was not the intended behavior.

CVE-2023-38545 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.7 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H).

3.2.2 EXTERNAL CONTROL OF FILE NAME OR PATH CWE-73

This flaw allows an attacker to insert cookies at will into a running program using libcurl, if the specific series of conditions are met. libcurl performs transfers. In its API, an application creates “easy handles” that are the individual handles for single transfers. libcurl provides a function call that duplicates an easy handle called curl_easy_duphandle. If a transfer has cookies enabled when the handle is duplicated, the cookie-enable state is also cloned – but without cloning the actual cookies. If the source handle did not read any cookies from a specific file on disk, the cloned version of the handle would instead store the file name as none (using the four ASCII letters, no quotes). Subsequent use of the cloned handle that does not explicitly set a source to load cookies from would then inadvertently load cookies from a file named none – if such a file exists and is readable in the current directory of the program using libcurl, and if using the correct file format of course.

CVE-2023-38546 has been assigned to this vulnerability. A CVSS v3.1 base score of 3.7 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N).

3.2.3 IMPROPER PRIVILEGE MANAGEMENT CWE-269

An improper privilege management vulnerability in a Fortinet FortiOS HA cluster version 7.4.0 through 7.4.1 and 7.2.5 and in a FortiProxy HA cluster version 7.4.0 through 7.4.1 allows an authenticated attacker to perform elevated actions via crafted HTTP or HTTPS requests.

CVE-2023-44250 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.2.4 UNCONTROLLED RESOURCE CONSUMPTION CWE-400

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

CVE-2023-44487 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).

A CVSS v4 score has been calculated for CVE-2023-44487. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.5 IMPROPER CERTIFICATE VALIDATION CWE-295

An improper certificate validation vulnerability in Fortinet FortiOS 7.0.0 – 7.0.13, 7.2.0 – 7.2.6 and 7.4.0 – 7.4.1 allows a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the FortiLink communication channel between the FortiOS device and FortiSwitch.

CVE-2023-47537 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:H/PR:N/UI:N/S:U/C:L/I:L/A:N).

3.2.6 OUT-OF-BOUNDS WRITE CWE-787

A out-of-bounds write vulnerability in Fortinet FortiOS versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.6, 7.0.0 through 7.0.13, 6.4.0 through 6.4.14, 6.2.0 through 6.2.15, 6.0.0 through 6.0.17, FortiProxy versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.8, 7.0.0 through 7.0.14, 2.0.0 through 2.0.13, 1.2.0 through 1.2.13, 1.1.0 through 1.1.6, 1.0.0 through 1.0.7 allows attacker to execute unauthorized code or commands via specifically crafted requests.

CVE-2024-21762 has been assigned to this vulnerability. A CVSS v3.1 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).

3.2.7 USE OF EXTERNALLY-CONTROLLED FORMAT STRING CWE-134

A use of externally-controlled format string vulnerability in FortiOS fgfmd daemon may allow
a remote unauthenticated attacker to execute arbitrary code or commands via specially crafted requests.

CVE-2024-23113 has been assigned to this vulnerability. A CVSS v3.1 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

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:

RUGGEDCOM APE1808: Contact customer support to receive patch and update information.

RUGGEDCOM APE1808 (CVE-2024-21762): Disable SSL VPN (disable webmode is NOT a valid workaround) (see https://www.fortiguard.com/psirt/FG-IR-24-015).

RUGGEDCOM APE1808 (CVE-2024-23113): For each interface, remove the fgfm access (see https://www.fortiguard.com/psirt/FG-IR-24-029).

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-832273 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.

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

5. UPDATE HISTORY

March 14, 2024: Initial Publication