SSA-114589: Multiple Vulnerabilities in Nucleus RTOS based APOGEE, TALON and Desigo PXC/PXM Products
Publication Date:
2021-11-09
Last Update:
2022-05-10
Current Version:
V1.3
CVSS v3.1 Base Score:
9.8
SUMMARY
Multiple vulnerabilities (also known as “NUCLEUS:13”) have been identified in the Nucleus RTOS (real-time operating system) and reported in the Siemens Security Advisory SSA-044112: https://cert-portal.siemens.com/productcert/pdf/ssa-044112.pdf .
The products listed below use affected versions of the Nucleus software and inherently contain these vulnerabilities.
Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.
AFFECTED PRODUCTS AND SOLUTION
WORKAROUNDS AND MITIGATIONS
Siemens has identified the following specific workarounds and mitigations that customers can apply to reduce the risk:
CVE-2021-31881, CVE-2021-31882, CVE-2021-31883, CVE-2021-31884: Disable the DHCP client and use static IP address configuration instead (Note that the DHCP client is disabled by default on APOGEE/TALON and Desigo products.)
CVE-2021-31885, CVE-2021-31886, CVE-2021-31887, CVE-2021-31888: Disable the FTP service (Note that the FTP service is disabled by default on Desigo products.)
Product specific remediations or mitigations can be found in the section Affected Products and Solution .General Security Recommendations .
GENERAL SECURITY RECOMMENDATIONS
As a general security measure Siemens strongly recommends to protect network access to affected products with appropriate mechanisms. It is advised to follow recommended security practices in order to run the devices in a protected IT environment.
PRODUCT DESCRIPTION
The APOGEE MEC and the MBC are high-performance Direct Digital Control (DDC) devices and are an integral part of the APOGEE Automation System.
The APOGEE PXC Modular and Compact Series are high-performance Direct Digital Control (DDC) devices and an integral part of the APOGEE Automation System.
The Desigo PX automation stations and operator units control and monitor building automation systems. They allow for alarm signaling, time-based programs and trend logging.
The TALON TC Modular and Compact Series are high-performance Direct Digital Control (DDC) devices and an integral part of the TALON Automation System.
VULNERABILITY CLASSIFICATION
The vulnerability classification has been performed by using the CVSS scoring system in version 3.1
(CVSS v3.1) (https://www.first.org/cvss ). The CVSS environmental score is specific to the customer’s
environment and will impact the overall CVSS score. The environmental score should therefore be
individually defined by the customer to accomplish final scoring.
An additional classification has been performed using the CWE classification, a community-developed
list of common software security weaknesses. This serves as a common language and as a baseline for
weakness identification, mitigation, and prevention efforts. A detailed list of CWE classes can be found
at: https://cwe.mitre.org/ .
Vulnerability CVE-2021-31344
ICMP echo packets with fake IP options allow sending ICMP echo reply messages to arbitrary hosts on the network. (FSMD-2021-0004)
Vulnerability CVE-2021-31345
The total length of an UDP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on a user-defined applications that runs on top of the UDP protocol. (FSMD-2021-0006)
Vulnerability CVE-2021-31346
The total length of an ICMP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on the network buffer organization in memory. (FSMD-2021-0007)
Vulnerability CVE-2021-31881
When processing a DHCP OFFER message, the DHCP client application does not validate the length of the Vendor option(s), leading to Denial-of-Service conditions. (FSMD-2021-0008)
Vulnerability CVE-2021-31882
The DHCP client application does not validate the length of the Domain Name Server IP option(s) (0x06) when processing DHCP ACK packets. This may lead to Denial-of-Service conditions. (FSMD-2021-0011)
Vulnerability CVE-2021-31883
When processing a DHCP ACK message, the DHCP client application does not validate the length of the Vendor option(s), leading to Denial-of-Service conditions. (FSMD-2021-0013)
Vulnerability CVE-2021-31884
The DHCP client application assumes that the data supplied with the “Hostname” DHCP option is NULL terminated. In cases when global hostname variable is not defined, this may lead to Out-of-bound reads, writes, and Denial-of-service conditions. (FSMD-2021-0014)
Vulnerability CVE-2021-31885
TFTP server application allows for reading the contents of the TFTP memory buffer via sending malformed TFTP commands. (FSMD-2021-0009)
Vulnerability CVE-2021-31886
FTP server does not properly validate the length of the “USER” command, leading to stack-based buffer overflows. This may result in Denial-of-Service conditions and Remote Code Execution. (FSMD-2021-0010)
Vulnerability CVE-2021-31887
FTP server does not properly validate the length of the “PWD/XPWD” command, leading to stack-based buffer overflows. This may result in Denial-of-Service conditions and Remote Code Execution. (FSMD-2021-0016)
Vulnerability CVE-2021-31888
FTP server does not properly validate the length of the “MKD/XMKD” command, leading to stack-based buffer overflows. This may result in Denial-of-Service conditions and Remote Code Execution. (FSMD-2021-0018)
Vulnerability CVE-2021-31889
Malformed TCP packets with a corrupted SACK option leads to Information Leaks and Denial-of-Service conditions. (FSMD-2021-0015)
Vulnerability CVE-2021-31890
The total length of an TCP payload (set in the IP header) is unchecked. This may lead to various side effects, including Information Leak and Denial-of-Service conditions, depending on the network buffer organization in memory. (FSMD-2021-0017)
ADDITIONAL INFORMATION
Siemens is working to develop a solution to resolve the issues identified with the emphasis on addressing vulnerabilities that do not have a specific mitigation first.
Products listed in this advisory use the Nucleus RTOS (Real-time operating system).
For more details regarding the vulnerabilities reported for Nucleus RTOS refer to Siemens Security Advisory SSA-044112: https://cert-portal.siemens.com/productcert/pdf/ssa-044112.pdf For further inquiries on security vulnerabilities in Siemens products and solutions, please contact
the Siemens ProductCERT:
https://www.siemens.com/cert/advisories
HISTORY DATA
V1.0 (2021-11-09): Publication Date
V1.1 (2021-12-14): Added affected Desigo PXC/PXM products; updated corresponding mitigation measures; informed about planned solutions
V1.2 (2022-04-12): Added solutions for APOGEE PXC Compact (BACnet), APOGEE PXC Modular (BACnet), TALON TC Compact (BACnet), and TALON TC Modular (BACnet) products
V1.3 (2022-05-10): Added solutions for APOGEE PXC Compact (P2 Ethernet), APOGEE PXC Modular (P2 Ethernet), Desigo PXC Products, Desigo PXM Products
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